Contact-activated extended wear electrocardiography and physiological sensor monitor recorder

ABSTRACT

Physiological monitoring can be provided through a wearable monitor that includes two components, a flexible extended wear electrode patch and a removable reusable monitor recorder. The wearable monitor sits centrally on the patient&#39;s chest along the sternum oriented top-to-bottom. The placement of the wearable monitor in a location at the sternal midline (or immediately to either side of the sternum) benefits extended wear by removing the requirement that ECG electrodes be continually placed in the same spots on the skin throughout the monitoring period. The wearable monitor can interoperate wirelessly with other physiology and activity sensors and mobile devices, and can include cellular phone capabilities. The power usage of the wireless communication can be reduced by using a low energy wireless transceiver in the monitor. The monitor detects that the monitor has been adhered to the patient and begin collecting physiological data after such detection, preserving battery power.

CROSS-REFERENCE TO RELATED APPLICATION

This present non-provisional patent application is acontinuation-in-part of U.S. Pat. No. 10,165,946, issued Jan. 1, 2018;which is a continuation-in-part of U.S. Pat. No. 9,433,367, issued Sep.6, 2016; which is a continuation-in-part of U.S. Pat. No. 9,545,204,issued Jan. 17, 2017, and a continuation-in-part of U.S. Pat. No.9,730,593, issued Aug. 15, 2017, and which further claims priority under35 U.S.C. § 119(e) to U.S. Provisional Patent application, Ser. No.61/882,403, filed Sep. 25, 2013, the disclosures of which areincorporated by reference; this present non-provisional patentapplication is also a continuation-in-part of U.S. Pat. No. 9,700,227,issued Jul. 11, 2007, which is a continuation-in-part of U.S. Pat. No.9,730,593, issued Aug. 15, 2017, and further claims priority under 35U.S.C. § 119(e) to U.S. Provisional Patent application, Ser. No.61/882,403, filed Sep. 25, 2013, the disclosures of which areincorporated by reference.

FIELD

This application relates in general to electrocardiographic monitoringand, in particular, to a contact-activated extended wearelectrocardiography and physiological sensor monitor recorder.

BACKGROUND

The first electrocardiogram (ECG) was invented by a Dutch physiologist,Willem Einthoven, in 1903, who used a string galvanometer to measure theelectrical activity of the heart. Generations of physicians around theworld have since used ECGs, in various forms, to diagnose heart problemsand other potential medical concerns. Although the basic principlesunderlying Dr. Einthoven's original work, including his naming ofvarious waveform deflections (Einthoven's triangle), are stillapplicable today, ECG machines have evolved from his original three-leadECG, to ECGs with unipolar leads connected to a central referenceterminal starting in 1934, to augmented unipolar leads beginning in1942, and finally to the 12-lead ECG standardized by the American HeartAssociation in 1954 and still in use today. Further advances inportability and computerized interpretation have been made, yet theelectronic design of the ECG recording apparatuses has remainedfundamentally the same for much of the past 40 years.

Essentially, an ECG measures the electrical signals emitted by the heartas generated by the propagation of the action potentials that triggerdepolarization of heart fibers. Physiologically, transmembrane ioniccurrents are generated within the heart during cardiac activation andrecovery sequences. Cardiac depolarization originates high in the rightatrium in the sinoatrial (SA) node before spreading leftward towards theleft atrium and inferiorly towards the atrioventricular (AV) node. Aftera delay occasioned by the AV node, the depolarization impulse transitsthe Bundle of His and moves into the right and left bundle branches andPurkinje fibers to activate the right and left ventricles.

During each cardiac cycle, the ionic currents create an electrical fieldin and around the heart that can be detected by ECG electrodes placed onthe skin. Cardiac electrical activity is then visually represented in anECG trace by PQRSTU-waveforms. The P-wave represents atrial electricalactivity, and the QRSTU components represent ventricular electricalactivity. Specifically, a P-wave represents atrial depolarization, whichcauses atrial contraction.

P-wave analysis based on ECG monitoring is critical to accurate cardiacrhythm diagnosis and focuses on localizing the sites of origin andpathways of arrhythmic conditions. P-wave analysis is also used in thediagnosis of other medical disorders, including imbalance of bloodchemistry. Cardiac arrhythmias are defined by the morphology of P-wavesand their relationship to QRS intervals. For instance, atrialfibrillation (AF), an abnormally rapid heart rhythm, can be confirmed bythe presence of erratic atrial activity or the absence of distinctP-waves and an irregular ventricular rate. Atrial flutter can bediagnosed with characteristic “sawtooth” P-waves often occurring twicefor each QRS wave. Some congenital supraventricular tachycardias, likeAV node re-entry and atrioventricular reentrant tachycardia using aconcealed bypass tract, are characterized by an inverted P-waveoccurring shortly after the QRS wave. Similarly, sinoatrial block ischaracterized by a delay in the onset of P-waves, while junctionalrhythm, an abnormal heart rhythm resulting from impulses coming from alocus of tissue in the area of the AV node, usually presents withoutP-waves or with inverted P-waves within or shortly before or after theQRS wave. Also, the amplitudes of P-waves are valuable for diagnosis.The presence of broad, notched P-waves can indicate left atrialenlargement or disease. Conversely, the presence of tall, peakedP-waves, especially in the initial half, can indicate right atrialenlargement. Finally, P-waves with increased amplitude can indicatehypokalemia, caused by low blood potassium, whereas P-waves withdecreased amplitude can indicate hyperkalemia, caused by elevated bloodpotassium.

Cardiac rhythm disorders may present with lightheadedness, fainting,chest pain, hypoxia, syncope, palpitations, and congestive heart failure(CHF), yet rhythm disorders are often sporadic in occurrence and may notshow up in-clinic during a conventional 12-second ECG. Some atrialrhythm disorders, like atrial fibrillation, are known to cause stroke,even when intermittent. Continuous ECG monitoring with P-wave-centricaction potential acquisition over an extended period is more apt tocapture sporadic cardiac events that can be specifically identified anddiagnosed. However, recording sufficient ECG and related physiologicaldata over an extended period remains a significant challenge, despite anover 40-year history of ambulatory ECG monitoring efforts combined withno appreciable improvement in P-wave acquisition techniques since Dr.Einthoven's original pioneering work over a 110 years ago.

Electrocardiographic monitoring over an extended period provides aphysician with the kinds of data essential to identifying the underlyingcause of sporadic cardiac conditions, especially rhythm disorders, andother physiological events of potential concern. A 30-day observationperiod is considered the “gold standard” of monitoring by some, yet a14-day observation period is currently deemed more achievable byconventional ECG monitoring approaches. Realizing a 30-day observationperiod has proven unworkable with existing ECG monitoring systems, whichare arduous to employ; cumbersome, uncomfortable and not user-friendlyto the patient; and costly to manufacture and deploy. An intractableproblem is the inability to have the monitoring electrodes adhere to theskin for periods of time exceeding 5-14 days, let alone 30 days. Still,if a patient's ECG could be recorded in an ambulatory setting over aprolonged time periods, particularly for more than 14 days, the chancesof acquiring meaningful medical information and capturing an abnormalevent while the patient is engaged in normal activities are greatlyimproved.

The location of the atria and their low amplitude, low frequency contentelectrical signals make P-waves difficult to sense, particularly throughambulatory ECG monitoring. The atria are located either immediatelybehind the mid sternum (upper anterior right atrium) or posteriorlywithin the chest (left atrium), and their physical distance from theskin surface, especially when standard ECG monitoring locations areused, adversely affects current strength and signal fidelity. Cardiacelectrical potentials measured from the classical dermal locations havean amplitude of only one-percent of the amplitude of transmembraneelectrical potentials. The distance between the heart and ECG electrodesreduces the magnitude of electrical potentials in proportion to thesquare of change in distance, which compounds the problem of sensing lowamplitude P-waves. Moreover, the tissues and structures that lie betweenthe activation regions within the heart and the body's surface furtherattenuate the cardiac electrical field due to changes in the electricalresistivity of adjacent tissues. Thus, surface electrical potentials,when even capable of being accurately detected, are smoothed over inaspect and bear only a general spatial relationship to actual underlyingcardiac events, thereby complicating diagnosis. Conventional 12-leadECGs attempt to compensate for weak P-wave signals by monitoring theheart from multiple perspectives and angles, while conventionalambulatory ECGs primarily focus on monitoring higher amplitudeventricular activity, i.e., the R-wave, that, comparatively, can bereadily sensed. Both approaches are relatively unsatisfactory withrespect to the P-wave and related need for the accurate acquisition ofthe P and R-wave medically actionable data of the myriad cardiac rhythmdisorders that exist.

Additionally, maintaining continual contact between ECG electrodes andthe skin after a day or two of ambulatory ECG monitoring has been aproblem. Time, dirt, moisture, and other environmental contaminants, aswell as perspiration, skin oil, and dead skin cells from the patient'sbody, can get between an ECG electrode's non-conductive adhesive and theskin's surface. These factors adversely affect electrode adhesion whichin turn adversely affects the quality of cardiac signal recordings.Furthermore, the physical movements of the patient and their clothingimpart various compressional, tensile, bending, and torsional forces onthe contact point of an ECG electrode, especially over long recordingtimes, and an inflexibly fastened ECG electrode will be prone tobecoming dislodged or unattached. Moreover, subtle dislodgment may occurand be unbeknownst to the patient, making the ECG recordings worthless.Further, some patients may have skin that is susceptible to itching orirritation, and the wearing of ECG electrodes can aggravate such skinconditions. Thus, a patient may want or need to periodically remove orreplace ECG electrodes during a long-term ECG monitoring period, whetherto replace a dislodged electrode, reestablish better adhesion, alleviateitching or irritation, allow for cleansing of the skin, allow forshowering and exercise, or for other purpose. Such replacement or slightalteration in electrode location actually facilitates the goal ofrecording the ECG signal for long periods of time.

Conventionally, multi-week or multi-month monitoring can be performed byimplantable ECG monitors, such as the Reveal LINQ insertable cardiacmonitor, manufactured by Medtronic, Inc., Minneapolis, Minn. Thismonitor can detect and record paroxysmal or asymptomatic arrhythmias forup to three years. However, like all forms of implantable medical device(IMD), use of this monitor requires invasive surgical implantation,which significantly increases costs; requires ongoing follow up by aphysician throughout the period of implantation; requires specializedequipment to retrieve monitoring data; and carries complicationsattendant to all surgery, including risks of infection, injury or death.Finally, such devices do not necessarily avoid the problem of signalnoise and recording high quality signals.

Holter monitors are widely used for ambulatory ECG monitoring.Typically, they are used for only 24-48 hours. A typical Holter monitoris a wearable and portable version of an ECG that includes cables foreach electrode placed on the skin and a separate battery-powered ECGrecorder. The leads are placed in the anterior thoracic region in amanner similar to what is done with an in-clinic standard ECG machineusing electrode locations that are not specifically intended for optimalP-wave capture but more to identify events in the ventricles bycapturing the R-wave. The duration of monitoring depends on the sensingand storage capabilities of the monitor. A “looping” Holter (or event)monitor can operate for a longer period of time by overwriting older ECGtracings, thence “recycling” storage in favor of extended operation, yetat the risk of losing event data. Although capable of extended ECGmonitoring, Holter monitors are cumbersome, expensive and typically onlyavailable by medical prescription, which limits their usability.Further, the skill required to properly place the electrodes on thepatient's chest precludes a patient from replacing or removing thesensing leads and usually involves moving the patient from the physicianoffice to a specialized center within the hospital or clinic.

U.S. Pat. No. 8,460,189, to Libbus et al. (“Libbus”) discloses anadherent wearable cardiac monitor that includes at least two measurementelectrodes and an accelerometer. The device includes a reusableelectronics module and a disposable adherent patch that includes theelectrodes. ECG monitoring can be conducted using multiple disposablepatches adhered to different locations on the patient's body. The deviceincludes a processor configured to control collection and transmissionof data from ECG circuitry, including generating and processing of ECGsignals and data acquired from two or more electrodes. The ECG circuitrycan be coupled to the electrodes in many ways to define an ECG vector,and the orientation of the ECG vector can be determined in response tothe polarity of the measurement electrodes and orientation of theelectrode measurement axis. The accelerometer can be used to determinethe orientation of the measurement electrodes in each of the locations.The ECG signals measured at different locations can be rotated based onthe accelerometer data to modify amplitude and direction of the ECGfeatures to approximate a standard ECG vector. The signals recorded atdifferent locations can be combined by summing a scaled version of eachsignal. Libbus further discloses that inner ECG electrodes may bepositioned near outer electrodes to increase the voltage of measured ECGsignals. However, Libbus treats ECG signal acquisition as themeasurement of a simple aggregate directional data signal withoutdifferentiating between the distinct kinds of cardiac electricalactivities presented with an ECG waveform, particularly atrial (P-wave)activity.

The ZIO XT Patch and ZIO Event Card devices, manufactured by iRhythmTech., Inc., San Francisco, Calif., are wearable monitoring devices thatare typically worn on the upper left pectoral region to respectivelyprovide continuous and looping ECG recording. The location is used tosimulate surgically implanted monitors, but without specificallyenhancing P-wave capture. Both of these devices are prescription-onlyand for single patient use. The ZIO XT Patch device is limited to a14-day period, while the electrodes only of the ZIO Event Card devicecan be worn for up to 30 days. The ZIO XT Patch device combines bothelectronic recordation components and physical electrodes into a unitaryassembly that adheres to the patient's skin. The ZIO XT Patch deviceuses adhesive sufficiently strong to support the weight of both themonitor and the electrodes over an extended period and to resistdisadherence from the patient's body, albeit at the cost of disallowingremoval or relocation during the monitoring period. The ZIO Event Carddevice is a form of downsized Holter monitor with a recorder componentthat must be removed temporarily during baths or other activities thatcould damage the non-waterproof electronics. Both devices representcompromises between length of wear and quality of ECG monitoring.Neither is designed for a female-friendly fit or for recording of theatrial (P-wave) signals.

Personal ambulatory monitoring, both with smartphones or via adjuncts tosmartphones, such as with a wirelessly-connected monitor or activitytracker, of varying degrees of sophistication and interoperability, havebecome increasingly available. For instance, McManus et al., “A NovelApplication for the Detection of an Irregular Pulse using an iPhone 4Sin Patients with Atrial Fibrillation,” Vol. 10(3), pp. 315-319 (March2013), the disclosure of which is incorporated by reference, disclosesobtaining pulsatile time series recordings before and aftercardioversion using the digital camera built into a smartphone. Analgorithm implemented as an app executed by the smartphone analyzedrecorded signals to accurately distinguish pulse recordings duringatrial fibrillation from sinus rhythm, although such a smartphone-basedapproach provides non-continuous observation and would be impracticablefor long term physiological monitoring. Further, thesmartphone-implemented app does not provide continuous recordings,including the provision of pre-event and post-event context, both ofwhich are critical for an accurate medical diagnosis that might triggera meaningful and serious medical intervention. In addition, a physicianwould be loath to undertake a surgical or serious drug interventionwithout confirmatory evidence that the wearer in question was indeed thesubject of the presumed rhythm abnormality. Validation of authenticityof the rhythm disorder for a specified patient takes on critical legaland medical importance.

The AliveCor heart monitor, manufactured by AliveCor, Inc., SanFrancisco, Calif., provides a non-continuous, patient-triggered eventmonitor, which is worn on the fingertip. Heart rate is sensed over asingle lead (comparable to Lead I on a conventional ECG) and recorded byan app running on a smartphone, such as an iOS operating system-basedsmartphone, such as the iPhone, manufactured by Apple Inc., Cupertino,Calif., or an Android operating system-based smartphone, manufacturedand offered by various companies, including Google Inc., Mountain View,Calif.; Samsung Electronics Co., Ltd., Suwon, S. Korea; MotorolaMobility LLC, a subsidiary of Google Inc., Libertyville, Ill.; and LGElectronics Inc., Seoul, S. Korea. The Android operating system is alsolicensed by Google Inc. The app can send the data recorded by anAliveCor heart monitor from the smartphone to healthcare providers, whoultimately decide whether to use the data for screening or diagnosticpurposes. Furthermore, as explained supra with respect to the McManusreference, none of these devices provides the context of the arrhythmia,as well as the medico-legal confirmation that would otherwise allow fora genuine medical intervention.

Similarly, adherents to the so-called “Quantified Self” movement combinewearable sensors and wearable computing to self-track activities oftheir daily lives. The Fitbit Tracker, manufactured by Fitbit Inc., SanFrancisco, Calif.; the Jawbone UP, manufactured by Jawbone, SanFrancisco, Calif.; the Polar Loop, manufactured by Polar Electro,Kempele, Finland; and the Nike+FuelBand, manufactured by Nike Inc.,Beaverton, Oreg., for instance, provide activity trackers worn on thewrist or body with integrated fitness tracking features, such as a heartrate monitor and pedometer to temporally track the number of steps takeneach day with an estimation calories burned. The activity tracker caninterface with a smartphone or computer to allow a wearer to monitortheir progress towards a fitness goal. These activity trackers areaccessories to smartphones, including iOS operating system-basedsmartphones, Android operating system-based smartphones, and WindowsPhone operating-system based smartphones, such as manufactured byMicrosoft Corporation, Redmond, Wash., to which recorded data must beoffloaded for storage and viewing.

The features of activity trackers can also be increasingly found inso-called “smart” watches that combine many of the features of activitytrackers with smartphones. Entire product lines are beginning to beoffered to provide a range of fitness- and health-tracking solutions. Asone example, Samsung Electronics Co., Ltd., offers a line of mobileproducts with fitness-oriented features, including the Galaxy S5smartphone, which incorporates a biometric fingerprint reader and heartrate monitor; the Gear 2 smart watch, which also incorporates a heartrate monitor; and the Gear Fit wearable device, which incorporates aheart rate monitor, real time fitness coaching, and activity tracker.The Galaxy S5 smartphone's heart rate monitor is not meant forcontinuous tracking, while the both the Gear 2 smart watch and Gear Fitwearable device must be paired with a smartphone or computer to offloadand view the recorded data. Such a pairing requires the devices to beclose to each other and makes data offload challenging when a smartphoneor a computer are not at hand.

With all manner of conventional “fitness-oriented” devices, whethersmartphone, smart watch, or activity tracker, quantified physiology istypically tracked for only the personal use of the wearer. Monitoringcan be either continuous or non-continuous. The wearer must take extrasteps to route recorded data to a health care provider; thus, with rareexception, the data is not time-correlated to physician-supervisedmonitoring nor validated. Furthermore, the monitoring is strictlyinformational and medically-significant events, such as serious cardiacrhythm disorders, including tachyarrhythmias and bradyarrhythmias, whilepotentially detectable, are neither identified nor acted upon.

In today's medical and legal environment, a mobile device, such as asmartphone, provides information that seldom can be translated into datathat triggers surgery or drug therapy by a physician. In the case of asmartphone detecting a fast heartbeat, for example, such a detection andthe information on the smartphone would neither be identified as trulyrelated to the patient in question or would be deemed sufficient forsubjecting a patient to surgery or potentially toxic drug therapy. Thus,such data that is available today is not actionable in a medicallytherapeutic relevant way. To make such data actionable, one must haverecorded data that allows a specific rhythm diagnosis, and a vaguerecording hinting that something may be wrong with the heart will notsuffice. Further, the recorded data must not only identify theheart-related event of concern, but the signals before and after theevent, which provides critical medical information for a physician todiagnose the disorder specifically. Finally, the recorded data must bemade certifiable, so that the relationship of the recorded data to thepatient that the physician is seeing is clear and appropriatelyidentifiable as an event originating in the patient being examined.Establishing this relationship of data-to-patient has become a legallymandatory step in providing medical care, which heretofore has beenimpracticable insofar as one cannot merely rely upon a smartphone toprovide legally sufficient identification of an abnormality withactionable data such that a patient undergoes a serious medical orsurgical intervention commonly used in the management of heart rhythmdisorders.

Further, conventional wearable sensors are generally poorly-suited forcontinuous long-term monitoring due to inadequate power management andbecause of poor skin contact. Such devices can start trying to recordphysiological data, using up battery power, regardless of whether theyare currently being worn by a person whose physiological data thesensors are intended to gather. As a result of this battery power drain,the effective monitoring time for which these sensors can be used isreduced. The power drain can further be exacerbated by the wearabledevices performing functions other than physiological monitoring, suchas interfacing with other devices and transferring collected data tothese devices. For multi-purpose devices especially, such assmartphones, these additional activities can use up the majority of thebattery power, leaving insufficient power for continuous long-termmonitoring.

Therefore, a need remains for a low cost extended wear continuouslyrecording ECG monitor attuned to conserving power and capturing lowamplitude cardiac action potential propagation for arrhythmia diagnosis,particularly atrial activation P-waves, and practicably capable of beingworn for a long period of time, especially in patient's whose breastanatomy or size can interfere with signal quality in both women and men.

A further need remains for facilities to integrate wider-rangingphysiological and “life tracking”-type data into long-term ECG andphysiological data monitoring coupled with an onboard ability to cascadeinto the medical records and to the medical authorities appropriatemedical interventions upon detection of a condition of potential medicalconcern.

A still further need remains for a low cost extended wear continuouslyrecording ECG monitor attuned to capturing low amplitude cardiac actionpotential propagation for arrhythmia diagnosis, particularly atrialactivation P-waves, practicably capable of being worn for a long periodof time, especially in patient's whose breast anatomy or size caninterfere with signal quality in both women and men, and that is able tointerface with other devices that are distant from the monitor.

SUMMARY

Physiological monitoring can be provided through a lightweight wearablemonitor that includes two components, a flexible extended wear electrodepatch and a reusable monitor recorder that removably snaps into areceptacle on the electrode patch. The wearable monitor sits centrally(in the midline) on the patient's chest along the sternum orientedtop-to-bottom. The ECG electrodes on the electrode patch are tailored tobe positioned axially along the midline of the sternum for capturingaction potential propagation in an orientation that corresponds to theaVF lead used in a conventional 12-lead ECG that is used to sensepositive or upright P-waves. The placement of the wearable monitor in alocation at the sternal midline (or immediately to either side of thesternum), with its unique narrow “hourglass”-like shape, benefitslong-term extended wear by removing the requirement that ECG electrodesbe continually placed in the same spots on the skin throughout themonitoring period and significantly improves the ability of the wearablemonitor to cutaneously sense cardiac electrical potential signals,particularly the P-wave (or atrial activity) and, to a lesser extent,the QRS interval signals indicating ventricular activity in the ECGwaveforms. The patient is free to place an electrode patch anywherewithin the general region of the sternum, the area most likely to recordhigh quality atrial signals or P-waves. Moreover, the wearable monitoris worn in such a location that is comfortable to woman and allows wearduring activity.

Moreover, the electrocardiography monitor offers superior patientcomfort, convenience and user-friendliness. The electrode patch isspecifically designed for ease of use by a patient (or caregiver);assistance by professional medical personnel is not required. Thepatient is free to replace the electrode patch at any time and need notwait for a doctor's appointment to have a new electrode patch placed.Patients can easily be taught to find the familiar physical landmarks onthe body necessary for proper placement of the electrode patch.Empowering patients with the knowledge to place the electrode patch inthe right place ensures that the ECG electrodes will be correctlypositioned on the skin, no matter the number of times that the electrodepatch is replaced. In addition, the monitor recorder operatesautomatically and the patient only need snap the monitor recorder intoplace on the electrode patch to initiate ECG monitoring. Thus, thesynergistic combination of the electrode patch and monitor recordermakes the use of the electrocardiography monitor a reliable andvirtually foolproof way to monitor a patient's ECG and physiology for anextended, or even open-ended, period of time.

Further, the electrocardiography monitor is able to detect when themonitor is adhered to the patient and initiate the monitoring upondetecting the adherence, thus conserving battery power when compared toconventional monitors that go through monitoring steps regardless ofwhether they are attached to the patient. The detection can beaccomplished based on the electrocardiographic signals sensed by theelectrodes, using techniques such as measuring and analyzing voltageusing the electrographic electrodes that adhere to the patient's chest.In a further embodiment, the detection of the contact can beaccomplished by measuring impedance of the electrocardiographicelectrodes that adhere to the patient's chest. The detection of thecontact can be initiated based on receiving actigraphy data indicatingattachment to a patient, based on an expiration of a time interval, orbased on both factors.

In a further embodiment, the wearable monitor can interoperatewirelessly with other wearable physiology monitors and activity sensorsand with mobile devices, including so-called “smartphones,” as well aswith personal computers and tablet or handheld computers, to downloadmonitoring data either in real-time or in batches. The interoperationcan be accomplished by using a low energy wireless transceiver as partof the monitor, which can conserve battery power and allow for a longermonitoring period. Also, the wireless transceiver can be implementedusing a standard that allows the transceiver to have cellular phonecapabilities such as connecting to telecommunications networks, such asthe Internet or a cellular network, and interfacing with devices via thenetworks, extending the distance over which the interfacing can beaccomplished. Where a wearable physiology monitor, activity sensor, ormobile device worn or held by the patient includes the capability tosense cardiac activity, particularly heart rate, or other physiology, anapplication executed by the monitor, sensor, or device can trigger thedispatch of a medically-actionable wearable monitor to the patient upondetecting potentially medically-significant events, such as cardiacrhythm disorders, including tachyarrhythmias and bradyarrhythmias. Uponreceipt of the wearable monitor, the patient can use the sensor ordevice, if appropriately equipped with photographic, fingerprint orthumbprint, voice, or other recording features, to physically record theplacement and use of the wearable monitor, thereby facilitating theauthentication of the data recorded by the wearable monitor. Finally,the monitor wireless transceiver can also be used to either provide dataor other information to, or receive data or other information from, aninterfacing wearable physiology monitor, activity sensor, or mobiledevice for relay to an external system or further device, such as aserver, analysis, or for further legal validation of the relationship ofthe monitor to the patient, or for other purpose.

One embodiment provides a contact-activated extended wearelectrocardiography and physiological sensor monitor recorder. Therecorder includes a sealed housing adapted to be removably secured intoa non-conductive receptacle on a disposable extended wear electrodepatch and an electronic circuitry comprised within the sealed housing.The electronic circuitry includes an electrocardiographic front endcircuit electrically interfaced to the microcontroller and operable tosense electrocardiographic signals through electrocardiographicelectrodes provided on the disposable extended wear electrode patch,each of the electrocardiographic electrodes adapted to be positionedaxially along the midline of the sternum for capturing action potentialpropagation; an externally-powered microcontroller electricallyinterfaced to the front end and operable to execute under microprogrammable control through firmware that is stored in a program memoryunit of the microcontroller, the microcontroller operable to detect theelectrodes being adhered to the sternum based on the sensedelectrographic signals and to start an execution of a monitoringsequence stored as part of the firmware based on the detected adherence;and an externally-powered flash memory electrically interfaced with themicrocontroller and operable to store samples of theelectrocardiographic signals collected during the execution of themonitoring sequence.

A further embodiment provides a contact-activated ambulatoryelectrocardiography monitoring patch optimized for capturing lowamplitude cardiac action potential propagation. The monitoring patchincludes a disposable extended wear electrode patch and an ambulatoryelectrocardiography monitor. The disposable extended wear electrodepatch includes a flexible backing including stretchable material definedas an elongated strip with a narrow longitudinal midsection, each end ofthe flexible backing comprising an adhesive contact surface adapted toserve as a crimp relief; a pair of electrocardiographic electrodesincluded on the contact surface of each end of the flexible backing,each electrocardiographic electrode conductively exposed for dermaladhesion and adapted to be positioned axially along the midline of thesternum for capturing action potential propagation; a non-conductivereceptacle affixed to a non-contacting surface of the flexible backingand including an electro mechanical docking interface; and a pair offlexible circuit traces affixed at each end of the flexible backing witheach circuit trace connecting one of the electrocardiographic electrodesto the docking interface, at least one of the circuit traces adapted toextend along the narrow longitudinal midsection to serve as a strainrelief. The ambulatory electrocardiography monitor includes a wearablehousing adapted to securely fit into the receptacle and electroniccircuitry provided within the wearable housing and including an externalinterface configured to be removably connected to theelectrocardiographic electrodes via the docking interface. The circuitryfurther includes an electrocardiographic front end circuit adapted tosense cardiac electrical potential differentials through theelectrocardiographic electrodes; a low power microcontroller in controlof the front end and operable to execute over an extended period undermodular micro program control as specified in firmware, themicrocontroller further operable to receive the sensed cardiac potentialdifferentials as electrocardiographic signals representative ofamplitudes of the action potential propagation, to detect the electrodesadhered to the sternum based on the received electrocardiographicsignals and to start an execution of a monitoring sequence stored aspart of the firmware based on the detection of the adherence; and anon-volatile memory electrically interfaced with the microcontroller andoperable to continuously store samples of the electrocardiographicsignals collected during the execution of the monitoring sequencethroughout the extended period.

In a further embodiment, a wireless transceiver may also be attached tothe microcontroller to facilitate upload of data to monitoring device,or to receive data from additional sensors. The transceiver can beconfigured to connect to a telecommunications network, allowing toincrease a range over which the transceiver can interact with otherdevices.

The foregoing aspects enhance ECG monitoring performance and quality byfacilitating long-term ECG recording, which is critical to accuratediagnosis of cardiac rhythm disorders.

The monitoring patch is especially suited to the female anatomy,although also easily used over the male sternum. The narrow longitudinalisthmus or midsection can fit nicely within the inter-mammary cleft ofthe breasts without inducing discomfort, whereas conventional patchelectrodes are wide and, if adhered between the breasts, would causechafing, irritation, discomfort, and annoyance, leading to low patientcompliance.

In addition, the foregoing aspects enhance comfort in women (and certainmen), but not irritation of the breasts, by placing the monitoring patchin the best location possible for optimizing the recording of cardiacsignals from the atrium, particularly P-waves, which is another featurecritical to proper cardiac rhythm disorder diagnoses.

Finally, the foregoing aspects as relevant to monitoring are equallyapplicable to recording other physiological data, such as heart rate,temperature, blood pressure, respiratory rate, blood pressure, bloodsugar (with appropriate subcutaneous probe), oxygen saturation, minuteventilation, as well as other measures of body chemistry and physiology.

Still other embodiments will become readily apparent to those skilled inthe art from the following detailed description, wherein are describedembodiments by way of illustrating the best mode contemplated. As willbe realized, other and different embodiments are possible and theembodiments' several details are capable of modifications in variousobvious respects, all without departing from their spirit and the scope.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are diagrams showing, by way of examples, an extended wearelectrocardiography and physiological sensor monitor respectively fittedto the sternal region of a female patient and a male patient.

FIG. 3 is a functional block diagram showing a system for remoteinterfacing of a contact-activated extended wear electrocardiography andphysiological sensor monitor in accordance with one embodiment.

FIG. 4 is a perspective view showing a contact-activated extended wearelectrode patch with a monitor recorder inserted.

FIG. 5 is a perspective view showing the monitor recorder of FIG. 4.

FIG. 6 is a perspective view showing the extended wear electrode patchof FIG. 4 without a monitor recorder inserted.

FIG. 7 is a bottom plan view of the monitor recorder of FIG. 4.

FIG. 8 is a top view showing the flexible circuit of the extended wearelectrode patch of FIG. 4 when mounted above the flexible backing.

FIG. 9 is a functional block diagram showing the component architectureof the circuitry of the monitor recorder of FIG. 4.

FIG. 10 is a functional block diagram showing the circuitry of theextended wear electrode patch of FIG. 4.

FIG. 11 is a flow diagram showing a monitor recorder-implemented methodfor monitoring ECG data for use in the monitor recorder of FIG. 4.

FIG. 12 is a graph showing, by way of example, a typical ECG waveform.

FIG. 13 is a flow diagram showing a method for offloading and convertingECG and other physiological data from an extended wearelectrocardiography and physiological sensor monitor in accordance withone embodiment.

FIG. 14 is a front anatomical view showing, by way of illustration, thelocations of the heart and lungs within the rib cage of an adult human.

FIG. 15 is a schematic diagram showing the ECG front end circuit of thecircuitry of the monitor recorder of FIG. 9 in accordance with oneembodiment.

FIG. 16 is a functional block diagram showing the signal processingfunctionality of the microcontroller in accordance with one embodiment.

FIG. 17 is a functional block diagram showing operations performed bythe download station in accordance with one embodiment.

DETAILED DESCRIPTION

Physiological monitoring can be provided through a wearable monitor thatincludes two components, a flexible extended wear electrode patch and aremovable reusable monitor recorder. Both the electrode patch and themonitor recorder are optimized to capture electrical signals from thepropagation of low amplitude, relatively low frequency content cardiacaction potentials, particularly the P-waves generated during atrialactivation. FIGS. 1 and 2 are diagrams showing, by way of example, anextended wear electrocardiography and physiological sensor monitor 12,including a monitor recorder 14 in accordance with one embodiment,respectively fitted to the sternal region of a female patient 10 and amale patient 11. The wearable monitor 12 sits centrally (in the midline)on the patient's chest along the sternum 13 oriented top-to-bottom withthe monitor recorder 14 preferably situated towards the patient's head.In a further embodiment, the orientation of the wearable monitor 12 canbe corrected post-monitoring, as further described infra. The electrodepatch 15 is shaped to fit comfortably and conformal to the contours ofthe patient's chest approximately centered on the sternal midline 16 (orimmediately to either side of the sternum 13). The distal end of theelectrode patch 15 extends towards the Xiphoid process and, dependingupon the patient's build, may straddle the region over the Xiphoidprocess. The proximal end of the electrode patch 15, located under themonitor recorder 14, is below the manubrium and, depending uponpatient's build, may straddle the region over the manubrium.

During ECG monitoring, the amplitude and strength of action potentialssensed on the body's surface are affected to varying degrees by cardiac,cellular, extracellular, vector of current flow, and physical factors,like obesity, dermatitis, large breasts, and high impedance skin, as canoccur in dark-skinned individuals. Sensing along the sternal midline 16(or immediately to either side of the sternum 13) significantly improvesthe ability of the wearable monitor 12 to cutaneously sense cardiacelectric signals, particularly the P-wave (or atrial activity) and, to alesser extent, the QRS interval signals in the ECG waveforms thatindicate ventricular activity by countering some of the effects of thesefactors.

The ability to sense low amplitude, low frequency content body surfacepotentials is directly related to the location of ECG electrodes on theskin's surface and the ability of the sensing circuitry to capture theseelectrical signals. FIG. 14 is a front anatomical view showing, by wayof illustration, the locations of the heart 4 and lungs 5 within the ribcage of an adult human. Depending upon their placement locations on thechest, ECG electrodes may be separated from activation regions withinthe heart 4 by differing combinations of internal tissues and bodystructures, including heart muscle, intracardiac blood, the pericardium,intrathoracic blood and fluids, the lungs 5, skeletal muscle, bonestructure, subcutaneous fat, and the skin, plus any contaminants presentbetween the skin's surface and electrode signal pickups. The degree ofamplitude degradation of cardiac transmembrane potentials increases withthe number of tissue boundaries between the heart 4 and the skin'ssurface that are encountered. The cardiac electrical field is degradedeach time the transmembrane potentials encounter a physical boundaryseparating adjoining tissues due to differences in the respectivetissues' electrical resistances. In addition, other non-spatial factors,such as pericardial effusion, emphysema or fluid accumulation in thelungs, as further explained infra, can further degrade body surfacepotentials.

Internal tissues and body structures can adversely affect the currentstrength and signal fidelity of all body surface potentials, yet lowamplitude cardiac action potentials, particularly the P-wave with anormative amplitude of less than 0.25 microvolts (mV) and a normativeduration of less than 120 milliseconds (ms), are most apt to benegatively impacted. The atria 6 are generally located posteriorlywithin the thoracic cavity (with the exception of the anterior rightatrium and right atrial appendage), and, physically, the left atriumconstitutes the portion of the heart 4 furthest away from the surface ofthe skin on the anterior chest. Conversely, the ventricles 7, whichgenerate larger amplitude signals, generally are located anteriorly withthe anterior right ventricle and most of the left ventricle situatedrelatively close to the skin surface on the anterior chest, whichcontributes to the relatively stronger amplitudes of ventricularwaveforms. Thus, the quality of P-waves (and other already-low amplitudeaction potential signals) is more susceptible to weakening fromintervening tissues and structures than the waveforms associated withventricular activation.

The importance of the positioning of ECG electrodes along the sternalmidline 15 has largely been overlooked by conventional approaches to ECGmonitoring, in part due to the inability of their sensing circuitry toreliably detect low amplitude, low frequency content electrical signals,particularly in P-waves. In turn, that inability to keenly sense P-waveshas motivated ECG electrode placement in other non-sternal midlinethoracic locations, where the QRSTU components of the ECG that representventricular electrical activity are more readily detectable by theirsensing circuitry than P-waves. In addition, ECG electrode placementalong the sternal midline 15 presents major patient wearabilitychallenges, such as fitting a monitoring ensemble within the narrowconfines of the inter-mammary cleft between the breasts, that to largeextent drive physical packaging concerns, which can be incompatible withECG monitors intended for placement, say, in the upper pectoral regionor other non-sternal midline thoracic locations. In contrast, thewearable monitor 12 uses an electrode patch 15 that is specificallyintended for extended wear placement in a location at the sternalmidline 16 (or immediately to either side of the sternum 13). Whencombined with a monitor recorder 14 that uses sensing circuitryoptimized to preserve the characteristics of low amplitude cardiacaction potentials, especially those signals from the atria, as furtherdescribed infra with reference to FIG. 15, the electrode patch 15 helpsto significantly improve atrial activation (P-wave) sensing throughplacement in a body location that robustly minimizes the effects oftissue and body structure.

Referring back to FIGS. 1 and 2, the placement of the wearable monitor12 in the region of the sternal midline 13 puts the ECG electrodes ofthe electrode patch 15 in locations better adapted to sensing andrecording low amplitude cardiac action potentials during atrialpropagation (P-wave signals) than placement in other locations, such asthe upper left pectoral region, as commonly seen in most conventionalambulatory ECG monitors. The sternum 13 overlies the right atrium of theheart 4. As a result, action potential signals have to travel throughfewer layers of tissue and structure to reach the ECG electrodes of theelectrode patch 15 on the body's surface along the sternal midline 13when compared to other monitoring locations, a distinction that is ofcritical importance when capturing low frequency content electricalsignals, such as P-waves.

Moreover, cardiac action potential propagation travels simultaneouslyalong a north-to-south and right-to-left vector, beginning high in theright atrium and ultimately ending in the posterior and lateral regionof the left ventricle. Cardiac depolarization originates high in theright atrium in the SA node before concurrently spreading leftwardtowards the left atrium and inferiorly towards the AV node. The ECGelectrodes of the electrode patch 15 are placed with the upper orsuperior pole (ECG electrode) along the sternal midline 13 beneath themanubrium and the lower or inferior pole (ECG electrode) along thesternal midline 13 in the region of the Xiphoid process 9 and lowersternum. The ECG electrodes are placed primarily in a head-to-footorientation along the sternum 13 that corresponds to the head-to-footwaveform vector exhibited during atrial activation. This orientationcorresponds to the aVF lead used in a conventional 12-lead ECG that isused to sense positive or upright P-waves.

Furthermore, the thoracic region underlying the sternum 13 along themidline 16 between the manubrium 8 and Xiphoid process 9 is relativelyfree of lung tissue, musculature, and other internal body structuresthat could occlude the electrical signal path between the heart 4,particularly the atria, and ECG electrodes placed on the surface of theskin. Fewer obstructions means that cardiac electrical potentialsencounter fewer boundaries between different tissues. As a result, whencompared to other thoracic ECG sensing locations, the cardiac electricalfield is less altered when sensed dermally along the sternal midline 13.As well, the proximity of the sternal midline 16 to the ventricles 7facilitates sensing of right ventricular activity and provides superiorrecordation of the QRS interval, again, in part due to the relativelyclear electrical path between the heart 4 and the skin surface.

Finally, non-spatial factors can affect transmembrane action potentialshape and conductivity. For instance, myocardial ischemia, an acutecardiac condition, can cause a transient increase in blood perfusion inthe lungs 5. The perfused blood can significantly increase electricalresistance across the lungs 5 and therefore degrade transmission of thecardiac electrical field to the skin's surface. However, the placementof the wearable monitor 12 along the sternal midline 16 in theinter-mammary cleft between the breasts is relatively resilient to theadverse effects to cardiac action potential degradation caused byischemic conditions as the body surface potentials from a locationrelatively clear of underlying lung tissue and fat help compensate forthe loss of signal amplitude and content. The monitor recorder 14 isthus able to record the P-wave morphology that may be compromised bymyocardial ischemia and therefore make diagnosis of the specificarrhythmias that can be associated with myocardial ischemia moredifficult.

The placement of the wearable monitor 12 in a location at the sternalmidline 16 (or immediately to either side of the sternum 13)significantly improves the ability of the wearable monitor 12 tocutaneously sense cardiac electric signals, particularly the P-wave (oratrial activity) and, to a lesser extent, the QRS interval signals inthe ECG waveforms that indicate ventricular activity, whilesimultaneously facilitating comfortable long-term wear for many weeks.The sternum 13 overlies the right atrium of the heart and the placementof the wearable monitor 12 in the region of the sternal midline 13 putsthe ECG electrodes of the electrode patch 15 in a location betteradapted to sensing and recording P-wave signals than other placementlocations, say, the upper left pectoral region or lateral thoracicregion or the limb leads. In addition, placing the lower or inferiorpole (ECG electrode) of the electrode patch 15 over (or near) theXiphoid process facilitates sensing of ventricular activity and providesexcellent recordation of the QRS interval as the Xiphoid processoverlies the apical region of the ventricles.

When operated standalone, the monitor recorder 14 of the extended wearelectrocardiography and physiological sensor monitor 12 senses andrecords the patient's ECG data into an onboard memory. In addition, thewearable monitor 12 can interoperate with other devices. FIG. 3 is afunctional block diagram showing a system 120 for remote interfacing ofa contact-activated extended wear electrocardiography and physiologicalsensor monitor 12 in accordance with one embodiment. The monitorrecorder 14 is a reusable component that can be fitted during patientmonitoring into a non-conductive receptacle provided on the electrodepatch 15, as further described infra with reference to FIG. 4, and laterremoved for offloading of stored ECG data or to receive revisedprogramming. The monitor recorder 14 can then be connected to a downloadstation 125, which could be a programmer or other device that permitsthe retrieval of stored ECG monitoring data, execution of diagnostics onor programming of the monitor recorder 14, or performance of otherfunctions. The monitor recorder 14 has a set of electrical contacts (notshown) that enable the monitor recorder 14 to physically interface to aset of terminals 128 on a paired receptacle 127 of the download station125. In turn, the download station 125 executes a communications oroffload program 126 (“Offload”) or similar program that interacts withthe monitor recorder 14 via the physical interface to retrieve thestored ECG monitoring data. The download station 125 could be a server,personal computer, tablet or handheld computer, smart mobile device, orpurpose-built device designed specific to the task of interfacing with amonitor recorder 14. Still other forms of download station 125 arepossible. Also, as mentioned below, the data from the monitor 12 can beoffloaded wirelessly and the monitor 12 can interface with the downloadstation 125 wirelessly.

FIG. 17 is a functional block diagram showing the operations 180performed by the download station 125. The download station 125 isresponsible for offloading stored ECG monitoring data from a monitorrecorder 14 and includes an electro mechanical docking interface bywhich the monitor recorder 14 is connected at the external connector 65.The download station operates under programmable control as specified insoftware 181. The stored ECG monitoring data retrieved from storage 182on a monitor recorder 14 is first decompressed by a decompression module183, which converts the stored ECG monitoring data back into anuncompressed digital representation more suited to signal processingthan a compressed signal. The retrieved ECG monitoring data may bestored into local storage for archival purposes, either in originalcompressed form, or as uncompressed.

The download station can include an array of filtering modules. Forinstance, a set of phase distortion filtering tools 184 may be provided,where corresponding software filters can be provided for each filterimplemented in the firmware executed by the microcontroller 61. Thedigital signals are run through the software filters in a reversedirection to remove phase distortion. For instance, a 45 Hertz high passfilter in firmware may have a matching reverse 45 Hertz high pass filterin software. Most of the phase distortion is corrected, that is,canceled to eliminate noise at the set frequency, but data at otherfrequencies in the waveform remain unaltered. As well, bidirectionalimpulse infinite response (IIR) high pass filters and reverse direction(symmetric) IIR low pass filters can be provided. Data is run throughthese filters first in a forward direction, then in a reverse direction,which generates a square of the response and cancels out any phasedistortion. This type of signal processing is particularly helpful withimproving the display of the ST-segment by removing low frequency noise.

An automatic gain control (AGC) module 185 can also be provided toadjust the digital signals to a usable level based on peak or averagesignal level or other metric. AGC is particularly critical tosingle-lead ECG monitors, where physical factors, such as the tilt ofthe heart, can affect the electrical field generated. On three-leadHolter monitors, the leads are oriented in vertical, horizontal anddiagonal directions. As a result, the horizontal and diagonal leads maybe higher amplitude and ECG interpretation will be based on one or bothof the higher amplitude leads. In contrast, the electrocardiographymonitor 12 has only a single lead that is oriented in the verticaldirection, so variations in amplitude will be wider than available withmulti-lead monitors, which have alternate leads to fall back upon.

In addition, AGC may be necessary to maintain compatibility withexisting ECG interpretation software, which is typically calibrated formulti-lead ECG monitors for viewing signals over a narrow range ofamplitudes. Through the AGC module 185, the gain of signals recorded bythe monitor recorder 14 of the electrocardiography monitor 12 can beattenuated up (or down) to work with FDA-approved commercially availableECG interpretation.

AGC can be implemented in a fixed fashion that is uniformly applied toall signals in an ECG recording, adjusted as appropriate on arecording-by-recording basis. Typically, a fixed AGC value is calculatedbased on how an ECG recording is received to preserve the amplituderelationship between the signals. Alternatively, AGC can be varieddynamically throughout an ECG recording, where signals in differentsegments of an ECG recording are amplified up (or down) by differingamounts of gain.

Typically, the monitor recorder 14 will record a high resolution, lowfrequency signal for the P-wave segment. However, for some patients, theresult may still be a visually small signal. Although high resolution ispresent, the unaided eye will normally be unable to discern the P-wavesegment. Therefore, gaining the signal is critical to visually depictingP-wave detail. This technique works most efficaciously with a raw signalwith low noise and high resolution, as generated by the monitor recorder14. Automatic gain control applied to a high noise signal will onlyexacerbate noise content and be self-defeating.

Finally, the download station can include filtering modules specificallyintended to enhance P-wave content. For instance, a P-wave enhancementfilter 186, which is a form of pre-emphasis filter, can be applied tothe signal to restore missing frequency content or to correct phasedistortion. Still other filters and types of signal processing arepossible.

In addition to the processing described above, the download station canalso convert retrieved data into a format suitable for use by thirdparty post-monitoring analysis software, as further described below withreference to FIG. 13. Referring back to FIG. 3, the data processed bythe download station 125 can then be retrieved from the download station125 over a hard link 135 using a control program 137 (“Ctl”) oranalogous application executing on a personal computer 136 or otherconnectable computing device, via a communications link (not shown),whether wired or wireless, or by physical transfer of storage media (notshown). The personal computer 136 or other connectable device may alsoexecute middleware that converts ECG data and other information into aformat suitable for use by a third-party post-monitoring analysisprogram, as further described infra with reference to FIG. 13. Note thatformatted data stored on the personal computer 136 would have to bemaintained and safeguarded in the same manner as electronic medicalrecords (EMRs) 134 in the secure database 124, as further discussedinfra. In a further embodiment, the download station 125 is able todirectly interface with other devices over a computer communicationsnetwork 121, which could be some combination of a local area network anda wide area network, including the Internet or anothertelecommunications network, over a wired or wireless connection.

A client-server model could be used to employ a server 122 to remotelyinterface with the download station 125 over the network 121 andretrieve the formatted data or other information. The server 122executes a patient management program 123 (“Mgt”) or similar applicationthat stores the retrieved formatted data and other information in asecure database 124 cataloged in that patient's EMRs 134. In addition,the patient management program 123 could manage a subscription servicethat authorizes a monitor recorder 14 to operate for a set period oftime or under pre-defined operational parameters.

The patient management program 123, or other trusted application, alsomaintains and safeguards the secure database 124 to limit access topatient EMRs 134 to only authorized parties for appropriate medical orother uses, such as mandated by state or federal law, such as under theHealth Insurance Portability and Accountability Act (HIPAA) or per theEuropean Union's Data Protection Directive. For example, a physician mayseek to review and evaluate his patient's ECG monitoring data, assecurely stored in the secure database 124. The physician would executean application program 130 (“Pgm”), such as a post-monitoring ECGanalysis program, on a personal computer 129 or other connectablecomputing device, and, through the application 130, coordinate access tohis patient's EMRs 134 with the patient management program 123. Otherschemes and safeguards to protect and maintain the integrity of patientEMRs 134 are possible.

The wearable monitor 12 can interoperate wirelessly with other wearablephysiology monitors and activity sensors 131, such as activity trackersworn on the wrist or body, and with mobile devices 132, including smartwatches and smartphones. Wearable physiology monitors and activitysensors 131 encompass a wide range of wirelessly interconnectabledevices that measure or monitor a patient's physiological data, such asheart rate, temperature, blood pressure, respiratory rate, bloodpressure, blood sugar (with appropriate subcutaneous probe), oxygensaturation, minute ventilation, and so on; physical states, such asmovement, sleep, footsteps, and the like; and performance, includingcalories burned or estimated blood glucose level. The physiology sensorsin non-wearable mobile devices, particularly smartphones, are generallynot meant for continuous tracking and do not provide medically preciseand actionable data sufficient for a physician to prescribe a surgicalor serious drug intervention; such data can be considered screeninginformation that something may be wrong, but not data that provides thehighly precise information that may allow for a surgery, such asimplantation of a pacemaker for heart block or a defibrillator forventricular tachycardia, or the application of serious medications, likeblood thinners for atrial fibrillation or a cardiac ablation procedure.Such devices, like smartphones, are better suited to pre- andpost-exercise monitoring or as devices that can provide a signal thatsomething is wrong, but not in the sufficient detail and validation toallow for medical action. Conversely, medically actionable wearablesensors and devices sometimes provide continuous recording forrelatively short time periods, but must be paired with a smartphone orcomputer to offload and evaluate the recorded data, especially if thedata is of urgent concern.

Wearable physiology monitors and activity sensors 131, also known as“activity monitors,” and to a lesser extent, “fitness” sensor-equippedmobile devices 132, can trace their life-tracking origins to ambulatorydevices used within the medical community to sense and recordtraditional medical physiology that could be useful to a physician inarriving at a patient diagnosis or clinical trajectory, as well as fromoutside the medical community, from, for instance, sports or lifestyleproduct companies who seek to educate and assist individuals withself-quantifying interests. Data is typically tracked by the wearablephysiology monitors or activity sensors 131 and mobile device 132 foronly the personal use of the wearer. The physiological monitoring isstrictly informational, even where a device originated within themedical community, and the data is generally not time-correlated tophysician-supervised monitoring. Importantly, medically-significantevents, such as cardiac rhythm disorders, including tachyarrhythmias,like ventricular tachycardia or atrial fibrillation, andbradyarrhythmias, like heart block, while potentially detectable withthe appropriate diagnostic heuristics, are neither identified nor actedupon by the wearable physiology monitors and activity sensors 131 andthe mobile device 132.

Frequently, wearable physiology monitors and activity sensors 131 arecapable of wirelessly interfacing with mobile devices 132, particularlysmart mobile devices, including so-called “smartphones” and “smartwatches,” as well as with personal computers and tablet or handheldcomputers, to download monitoring data either in real-time or inbatches. The wireless interfacing of such activity monitors is generallyachieved using transceivers that provide low-power, short-range wirelesscommunications, such as Bluetooth, although some wearable physiologymonitors and activity sensors 131, like their mobile device cohorts,have transceivers that provide true wireless communications services,including 4G or better mobile telecommunications, over atelecommunications network. Other types of wireless and wiredinterfacing are possible.

Where the wearable physiology monitors and activity sensors 131 arepaired with a mobile device 132, the mobile device 132 executes anapplication (“App”) that can retrieve the data collected by the wearablephysiology monitor and activity sensor 131 and evaluate the data togenerate information of interest to the wearer, such as an estimation ofthe effectiveness of the wearer's exercise efforts. Where the wearablephysiology monitors and activity sensors 131 has sufficient onboardcomputational resources, the activity monitor itself executes an appwithout the need to relay data to a mobile device 132. Generally, suchmore computationally-capable wearable physiology monitors and activitysensors are also equipped with wireless communications servicestransceivers, such as found in some smart watches that combine thefeatures of activity monitors with mobile devices. Still other activitymonitor and mobile device functions on the collected data are possible.

In a further embodiment, a wearable physiology monitor, activity sensor131, or mobile device 132 worn or held by the patient 10, or otherwisebe used proximal to the patient's body, can be used to first obtain andthen work collaboratively with a more definitive monitor recorder 14 toenable the collection of physiology by the monitor recorder 14 before,during, and after potentially medically-significant events. The wearablephysiology monitor, activity sensor 131, or mobile device 132 must becapable of sensing cardiac activity, particularly heart rate or rhythm,or other types of physiology or measures, either directly or upon reviewof relayed data. Where the wearable physiology monitor or activitysensor 131 is paired with a mobile device 132, the mobile device 132serves as a relay device and executes an application that will triggerthe dispatch of a monitor recorder 14 to the patient 10 upon detectingpotentially medically-significant events in the data provided by thepaired activity monitor, such as cardiac rhythm disorders, includingtachyarrhythmias and bradyarrhythmias. If the mobile device 132 isitself performing the monitoring of the patient's physiology, the mobiledevice 132 executes an application that will trigger the dispatch of amonitor recorder 14 to the patient 10 in near-real time upon detectingpotentially medically-significant events, thereby avoiding the delayincurred by data relay from an activity monitor. Finally, if thewearable physiology monitor or activity sensor 131 has sufficientonboard computational resources and also is equipped with a wirelesscommunications services transceiver, the wearable physiology monitor oractivity sensor 131 effectively becomes the mobile device 132 andexecutes an application that will trigger the dispatch of a monitorrecorder 14 to the patient 10 in near-real time upon detectingpotentially medically-significant events without the need to firstinterface with a mobile device 132. Still other configurations of thedetection app are possible.

The act of triggering the dispatch of a monitor recorder 14 representsthe first step in a cascade of possible medical interventions ofpotentially increasing seriousness and urgency. Sensors 131 and devices133 are generally not capable of detecting and recording medicallyprecise and actionable data, whereas, as a device designed for extendedwear, the monitor recorder 14 continually monitors the patient'sphysiology over a long time period and will capture anymedically-actionable data leading up to, throughout the occurrence of,and following an event of potential medical concern.

The monitoring data recorded by the monitor recorder 14 can be uploadeddirectly into the patient's EMRs 134, either by using a mobile device132 as a conduit for communications with a server 122 coupled to asecure database 124 within which the patient's EMRs 134 are stored, ordirectly to the server 122, if the monitor recorder 14 is appropriatelyequipped with a wireless transceiver or similar external datacommunications interface, as further described infra. Thus, the datarecorded by the monitor recorder 14 would directly feed into thepatient's EMRs 134, thereby allowing the data to be made certifiable forimmediate use by a physician or healthcare provider. No intermediatesteps would be necessary when going from cutaneously sensing cardiacelectric signals and collecting the patient's physiology using a monitorrecorder 14 to presenting that recorded data to a physician orhealthcare provider for medical diagnosis and care. The direct feedingof data from the monitor recorder 14 to the EMRs 134 clearly establishesthe relationship of the data, as recorded by the monitor recorder 14, tothe patient 10 that the physician is seeing and appropriately identifiesany potentially medically-significant event recorded in the data asoriginating in the patient 10 and nobody else. Based on the monitoringdata, physicians and healthcare providers can rely on the data ascertifiable and can directly proceed with determining the appropriatecourse of treatment for the patient 10, including undertaking furthermedical interventions as appropriate. In a further embodiment, theserver 122 can evaluate the recorded data, as fed into the patient'sEMRs 134, to refer the patient 10 for medical care to a general practicephysician or medical specialist, for instance, a cardiacelectrophysiologist referral from a cardiologist when the recorded dataindicates an event of sufficient potential severity to warrant thepossible implantation of a pacemaker for heart block or a defibrillatorfor ventricular tachycardia. Other uses of the data recorded by themonitor recorder 14 are possible.

For instance, a patient 10 who has previously suffered heart failure isparticularly susceptible to ventricular tachycardia following a periodof exercise or strenuous physical activity. A wearable sensor 131 ordevice 133 that includes a heart rate monitor would be able to timelydetect an irregularity in heart rhythm. The application executed by thesensor 131 or device 133 allows those devices to take action bytriggering the dispatch of a monitor recorder 14 to the patient 10, eventhough the data recorded by the sensor 131 or device 133 is itselfgenerally medically-insufficient for purposes of diagnosis and care.Thus, rather than passively recording patient data, the sensor 131 ordevice 133 takes on an active role in initiating the provisioning ofmedical care to the patient 10 and starts a cascade of appropriatemedical interventions under the tutelage of and followed by physiciansand trained healthcare professionals.

In a still further embodiment, the monitor recorder 14 could upload anevent detection application to the sensor 131 or device 133 to enablethose devices to detect those types of potentially medically-significantevents, which would trigger the dispatch of a monitor recorder 14 to thepatient 10. Alternatively, the event detection application could bedownloaded to the sensor 131 or device 133 from an online applicationstore or similar online application repository. Finally, the monitorrecorder 14 could use the sensor 131 or device 133 to generate anappropriate alert, including contacting the patient's physician orhealthcare services, via wireless (or wired) communications, upondetecting a potentially medically-significant event or in response to apatient prompting.

The patient 10 could be notified by the sensor 131 or device 133,through the sensor's or device's user interface, that an event ofpotential medical concern has been detected coupled with an offer tohave a monitor recorder 14 sent out to the patient 10, assuming that thepatient 10 is not already wearing a monitor recorder 14. Alternatively,the sensor 131 or device 133 could unilaterally send out a request for amonitor recorder 14. The request for a monitor recorder 14 could be sentvia wireless (or wired) communications to the patient's physician, amedical service provider organization, a pharmacy, an emergency medicalservice, or other appropriate healthcare entity that would, in turn,physically provide the patient with a monitor recorder 14. The patient10 could also be told to pick up a monitor recorder 14 directly from oneof the above-identified sources.

Conventional Holter monitors, as well as the ZIO XT Patch and ZIO EventCard devices, described supra, are currently available only by aphysician's prescription for a specific patient 10. As a result, thephysiological data recorded by these monitors and devices are assumed byhealthcare professional to belong to the patient 10. In thisprescriptive medicine context, grave questions as to the authenticity ofthe patient's identity and the data recorded do not generally arise,although current medical practice still favors requesting affirmativepatient and caregiver identification at every step of healthcareprovisioning. As a device intended for adoption and usage broader thanprescriptive medicine, the monitor recorder 14 carries the potential tobe used by more than one individual, which can raise concerns as to theveracity of the data recorded.

In a still further embodiment, the mobile device 132, or, if properlyequipped, the activity monitor, can be used to help authenticate thepatient 10 at the outset of and throughout the monitoring period. Themobile device 132 (or activity monitor) must be appropriately equippedwith a digital camera or other feature capable of recording physicalindicia located within the proximity of the mobile device 132. Forinstance, the Samsung Galaxy S5 smartphone has both a biometricfingerprint reader and autofocusing digital camera built in. Uponreceipt of a monitor recorder 14, the patient 10 can use thephotographic or other recording features of the mobile device 132 (oractivity monitor) to physically record the placement and use of themonitor recorder 14. For instance, the patient 10 could take a pictureor make a video of the monitor recorder 14 using as applied to the chestusing the built-in digital camera. The patient 10 could also swipe afinger over the biometric fingerprint reader. Preferably, the patient 10would include both his or her face or similar uniquely-identifying marksor indicia, such as a scar, tattoo, body piercing, or RFID chip, plusany visible or electronic indicia on the outside of the monitorrecorder's housing, as further described infra with reference to FIG. 5,in the physical recording. The physical recording would then be sent bythe mobile device 132 (or activity monitor) via wireless (or wired)communications to the patient's physician's office or other appropriatecaregiver, thereby facilitating the authentication of the data recordedby the monitor recorder 14. Alternatively, the physical recording couldbe securely stored by the monitor recorder 14 as part of the monitoringdata set.

The mobile device 132 could also serve as a conduit for providing thedata collected by the wearable physiology monitor or activity sensor 131to a server 122, or, similarly, the wearable physiology monitor oractivity sensor 131 could itself directly provide the collected data tothe server 122. The server 122 could then merge the collected data intothe wearer's EMRs 134 in the secure database 124, if appropriate (andpermissible), or the server 122 could perform an analysis of thecollected data, perhaps based by comparison to a population of likewearers of the wearable physiology monitor or activity sensor 131. Stillother server 122 functions on the collected data are possible.

Finally, the monitor recorder 14 can also be equipped with a wirelesstransceiver, as further described infra with reference to FIGS. 9 and10. Thus, when wireless-enabled, both wearable physiology monitors,activity sensors 131, and mobile devices 132 can wirelessly interfacewith the monitor recorder 14, which could either provide data or otherinformation to, or receive data or other information from an interfacingdevice for relay to a further device, such as the server 122, analysis,or other purpose. In addition, the monitor recorder 14 could wirelesslyinterface directly with the server 122, personal computer 129, or othercomputing device connectable over the network 121, when the monitorrecorder 14 is appropriately equipped for interfacing with such devices.In one embodiment, network 121 can be a telecommunications network, suchas the Internet or a cellular network, and the wireless transceiver canhave at least some cellular phone capabilities, such as by being able toconnect to the telecommunications networks. For example, if implementedusing the standard such as Bluetooth® 4.2 standard or a Wi-Fi standard,the transceiver can connect to the Internet. Similarly, if implementedusing a cellular standard and including a cellular chipset, thetransceiver can connect to a cellular network as further describedbelow. Once connected, the monitor recorder 14 can interface with theabove-described devices via connecting to the telecommunicationsnetwork. Still other types of remote interfacing of the monitor recorder14 are possible.

During use, the electrode patch 15 is first adhesed to the skin alongthe sternal midline 16 (or immediately to either side of the sternum13). A monitor recorder 14 is then snapped into place on the electrodepatch 15 to initiate ECG monitoring, with the monitoring being initiatedupon the recorder 14 detecting contact with the patient 10, 11. FIG. 4is a perspective view showing a contact-activated extended wearelectrode patch 15 with a monitor recorder 14 in accordance with oneembodiment inserted. The body of the electrode patch 15 is preferablyconstructed using a flexible backing 20 formed as an elongated strip 21of wrap knit or similar stretchable material with a narrow longitudinalmid-section 23 evenly tapering inward from both sides. A pair ofcut-outs 22 between the distal and proximal ends of the electrode patch15 create a narrow longitudinal midsection 23 or “isthmus” and definesan elongated “hourglass”-like shape, when viewed from above. The upperpart of the “hourglass” is sized to allow an electrically non-conductivereceptacle 25, sits on top of the outward-facing surface of theelectrode patch 15, to be affixed to the electrode patch 15 with an ECGelectrode placed underneath on the patient-facing underside, or contact,surface of the electrode patch 15; the upper part of the “hourglass” hasa longer and wider profile (but still rounded and tapered to fitcomfortably between the breasts) than the lower part of the “hourglass,”which is sized primarily to allow just the placement of an ECG electrodeof appropriate shape and surface area to record the P-wave and the QRSsignals sufficiently given the inter-electrode spacing.

The electrode patch 15 incorporates features that significantly improvewearability, performance, and patient comfort throughout an extendedmonitoring period. During wear, the electrode patch 15 is susceptible topushing, pulling, and torqueing movements, including compressional andtorsional forces when the patient bends forward, and tensile andtorsional forces when the patient leans backwards. To counter thesestress forces, the electrode patch 15 incorporates strain and crimpreliefs, such as described in commonly-assigned U.S. Pat. No. 9,545,204,issued Jan. 17, 2017, the disclosure of which is incorporated byreference. In addition, the cut-outs 22 and longitudinal midsection 23help minimize interference with and discomfort to breast tissue,particularly in women (and gynecomastic men). The cut-outs 22 andlongitudinal midsection 23 further allow better conformity of theelectrode patch 15 to sternal bowing and to the narrow isthmus of flatskin that can occur along the bottom of the intermammary cleft betweenthe breasts, especially in buxom women. The cut-outs 22 and longitudinalmidsection 23 help the electrode patch 15 fit nicely between a pair offemale breasts in the intermammary cleft. Still other shapes, cut-outsand conformities to the electrode patch 15 are possible.

The monitor recorder 14 removably and reusably snaps into anelectrically non-conductive receptacle 25 during use. The monitorrecorder 14 contains electronic circuitry for recording and storing thepatient's electrocardiography as sensed via a pair of ECG electrodesprovided on the electrode patch 15, such as described incommonly-assigned U.S. Pat. No. 9,730,593, issued Aug. 15, 2017, thedisclosure which is incorporated by reference. The non-conductivereceptacle 25 is provided on the top surface of the flexible backing 20with a retention catch 26 and tension clip 27 molded into thenon-conductive receptacle 25 to conformably receive and securely holdthe monitor recorder 14 in place.

The monitor recorder 14 includes a sealed housing that snaps into placein the non-conductive receptacle 25. FIG. 5 is a perspective viewshowing the monitor recorder 14 of FIG. 4. The sealed housing 50 of themonitor recorder 14 intentionally has a rounded isoscelestrapezoidal-like shape 52, when viewed from above, such as described incommonly-assigned U.S. Design Pat. No. D717,955, issued Nov. 18, 2014,the disclosure of which is incorporated by reference. In addition, alabel, barcode, QR code, or other visible or electronic indicia isprinted on the outside of, applied to the outside of, or integrated intothe sealed housing 50 to uniquely identify the monitor recorder 14 andcan include a serial number, manufacturing lot number, date ofmanufacture, and so forth. The edges 51 along the top and bottomsurfaces are rounded for patient comfort. The sealed housing 50 isapproximately 47 mm long, 23 mm wide at the widest point, and 7 mm high,excluding a patient-operable tactile-feedback button 55. The sealedhousing 50 can be molded out of polycarbonate, ABS, or an alloy of thosetwo materials. The button 55 is waterproof and the button's top outersurface is molded silicon rubber or similar soft pliable material. Aretention detent 53 and tension detent 54 are molded along the edges ofthe top surface of the housing 50 to respectively engage the retentioncatch 26 and the tension clip 27 molded into non-conductive receptacle25. Other shapes, features, and conformities of the sealed housing 50are possible.

The electrode patch 15 is intended to be disposable. The monitorrecorder 14, however, is reusable and can be transferred to successiveelectrode patches 15 to ensure continuity of monitoring. The placementof the wearable monitor 12 in a location at the sternal midline 16 (orimmediately to either side of the sternum 13) benefits long-termextended wear by removing the requirement that ECG electrodes becontinually placed in the same spots on the skin throughout themonitoring period. Instead, the patient is free to place an electrodepatch 15 anywhere within the general region of the sternum 13.

As a result, at any point during ECG monitoring, the patient's skin isable to recover from the wearing of an electrode patch 15, whichincreases patient comfort and satisfaction, while the monitor recorder14 ensures ECG monitoring continuity with minimal effort. A monitorrecorder 14 is merely unsnapped from a worn out electrode patch 15, theworn out electrode patch 15 is removed from the skin, a new electrodepatch 15 is adhered to the skin, possibly in a new spot immediatelyadjacent to the earlier location, and the same monitor recorder 14 issnapped into the new electrode patch 15 to reinitiate and continue theECG monitoring.

During use, the electrode patch 15 is first adhered to the skin in thesternal region. FIG. 6 is a perspective view showing the extended wearelectrode patch 15 of FIG. 4 without a monitor recorder 14 inserted. Aflexible circuit 32 is adhered to each end of the flexible backing 20. Adistal circuit trace 33 and a proximal circuit trace (not shown)electrically couple ECG electrodes (not shown) to a pair of electricalpads 34. The electrical pads 34 are provided within a moisture-resistantseal 35 formed on the bottom surface of the non-conductive receptacle25. When the monitor recorder 14 is securely received into thenon-conductive receptacle 25, that is, snapped into place, theelectrical pads 34 interface to electrical contacts (not shown)protruding from the bottom surface of the monitor recorder 14, and themoisture-resistant seal 35 enables the monitor recorder 14 to be worn atall times, even during bathing or other activities that could expose themonitor recorder 14 to moisture.

In addition, a battery compartment 36 is formed on the bottom surface ofthe non-conductive receptacle 25, and a pair of battery leads (notshown) electrically interface the battery to another pair of theelectrical pads 34. The battery contained within the battery compartment35 can be replaceable, rechargeable or disposable.

The monitor recorder 14 draws power externally from the battery providedin the non-conductive receptacle 25, thereby uniquely obviating the needfor the monitor recorder 14 to carry a dedicated power source. FIG. 7 isa bottom plan view of the monitor recorder 14 of FIG. 4. A cavity 58 isformed on the bottom surface of the sealed housing 50 to accommodate theupward projection of the battery compartment 36 from the bottom surfaceof the non-conductive receptacle 25, when the monitor recorder 14 issecured in place on the non-conductive receptacle 25. A set ofelectrical contacts 56 protrude from the bottom surface of the sealedhousing 50 and are arranged in alignment with the electrical pads 34provided on the bottom surface of the non-conductive receptacle 25 toestablish electrical connections between the electrode patch 15 and themonitor recorder 14. In addition, a seal coupling 57 circumferentiallysurrounds the set of electrical contacts 56 and securely mates with themoisture-resistant seal 35 formed on the bottom surface of thenon-conductive receptacle 25.

The placement of the flexible backing 20 on the sternal midline 16 (orimmediately to either side of the sternum 13) also helps to minimize theside-to-side movement of the wearable monitor 12 in the left- andright-handed directions during wear. To counter the dislodgment of theflexible backing 20 due to compressional and torsional forces, a layerof non-irritating adhesive, such as hydrocolloid, is provided at leastpartially on the underside, or contact, surface of the flexible backing20, but only on the distal end 30 and the proximal end 31. As a result,the underside, or contact surface of the longitudinal midsection 23 doesnot have an adhesive layer and remains free to move relative to theskin. Thus, the longitudinal midsection 23 forms a crimp relief thatrespectively facilitates compression and twisting of the flexiblebacking 20 in response to compressional and torsional forces. Otherforms of flexible backing crimp reliefs are possible.

Unlike the flexible backing 20, the flexible circuit 32 is only able tobend and cannot stretch in a planar direction. The flexible circuit 32can be provided either above or below the flexible backing 20. FIG. 8 isa top view showing the flexible circuit 32 of the extended wearelectrode patch 15 of FIG. 4 when mounted above the flexible backing 20.A distal ECG electrode 38 and proximal ECG electrode 39 are respectivelycoupled to the distal and proximal ends of the flexible circuit 32. Astrain relief 40 is defined in the flexible circuit 32 at a locationthat is partially underneath the battery compartment 36 when theflexible circuit 32 is affixed to the flexible backing 20. The strainrelief 40 is laterally extendable to counter dislodgment of the ECGelectrodes 38, 39 due to tensile and torsional forces. A pair of strainrelief cutouts 41 partially extend transversely from each opposite sideof the flexible circuit 32 and continue longitudinally towards eachother to define in ‘S’-shaped pattern, when viewed from above. Thestrain relief respectively facilitates longitudinal extension andtwisting of the flexible circuit 32 in response to tensile and torsionalforces. Other forms of circuit board strain relief are possible. Otherforms of the patch 15 arc also possible. For example, in a furtherembodiment, the distal and proximal circuit traces are replaced withinterlaced or sewn-in flexible wires, as further described incommonly-assigned U.S. Pat. No. 9,717,432, issued Aug. 1, 2017, thedisclosure of which is incorporated by reference.

ECG monitoring and other functions performed by the monitor recorder 14are provided through a micro controlled architecture. FIG. 9 is afunctional block diagram showing the component architecture of thecircuitry 60 of the monitor recorder 14 of FIG. 4. The circuitry 60 isexternally powered through a battery provided in the non-conductivereceptacle 25 (shown in FIG. 6). Both power and raw ECG signals, whichoriginate in the pair of ECG electrodes 38, 39 (shown in FIG. 8) on thedistal and proximal ends of the electrode patch 15, are received throughan external connector 65 that mates with a corresponding physicalconnector on the electrode patch 15. The external connector 65 includesthe set of electrical contacts 56 that protrude from the bottom surfaceof the sealed housing 50 and which physically and electrically interfacewith the set of pads 34 provided on the bottom surface of thenon-conductive receptacle 25. The external connector includes electricalcontacts 56 for data download, microcontroller communications, power,analog inputs, and a peripheral expansion port. The arrangement of thepins on the electrical connector 65 of the monitor recorder 14 and thedevice into which the monitor recorder 14 is attached, whether anelectrode patch 15 or download station (not shown), follow the sameelectrical pin assignment convention to facilitate interoperability. Theexternal connector 65 also serves as a physical interface to a downloadstation that permits the retrieval of stored ECG monitoring data,communication with the monitor recorder 14, and performance of otherfunctions.

Operation of the circuitry 60 of the monitor recorder 14 is managed by amicrocontroller 61. The microcontroller 61 includes a program memoryunit containing internal flash memory that is readable and writeable.The internal flash memory can also be programmed externally. Themicrocontroller 61 draws power externally from the battery provided onthe electrode patch 15 via a pair of the electrical contacts 56. Themicrocontroller 61 connects to the ECG front end circuit 63 thatmeasures raw cutaneous electrical signals and generates an analog ECGsignal representative of the electrical activity of the patient's heartover time.

The microcontroller 61 operates under modular micro program control asspecified in firmware, and the program control includes processing ofthe analog ECG signal output by the ECG front end circuit 63. FIG. 16 isa functional block diagram showing the signal processing functionality170 of the microcontroller 61 in accordance with one embodiment. Themicrocontroller 61 operates under modular micro program control asspecified in firmware 172. The firmware modules 172 may include high andlow pass filtering 173, and compression 174. Other modules are possible.The microcontroller 61 has a built-in ADC, although ADC functionalitycould also be provided in an external chip 172.

The ECG front end circuit 63 first outputs an analog ECG signal, whichthe ADC 171 acquires, samples and converts into an uncompressed digitalrepresentation. The microcontroller 61 includes one or more firmwaremodules 173 that perform filtering. In one embodiment, a high passsmoothing filter is used for the filtering; other filters andcombinations of high pass and low pass filters are possible in a furtherembodiment. Following filtering, the digital representation of thecardiac activation wave front amplitudes are compressed by one or morecompression modules 174 before being written out to storage 175.

As further described below with reference to FIG. 11, themicrocontroller 61 can check for whether electrodes 38, 39 (and thus themonitor 12 as a whole) are adhered to a patient 10, 11, prior tobeginning collecting physiological data. The microcontroller 61 candetermine the adherence based on the action potentials sensed by thefront end 63 through the electrodes 38, 39. When the monitor 12 isadhered to the patient's 10, 11 body, and in particular the sternum 13,the front end can sense 63 body surface potentials through theelectrodes 38, 39. The microcontroller 61 can distinguish the signalssensed by the front end 63 through the electrodes 38, 39 that are due tothe cardiac action potentials from other kinds of electrical signalsthat are not indicative of the monitor 12 being in contact with thesternum 13. For example, the front end 63 can measure voltage throughthe electrodes 38, 39, and the microcontroller 61 can process themeasured voltage to determine if the electrodes 38, 39 are sensingcardiac action potentials. For example, if an ECG waveform that resultsfrom the processing of the measured voltage is a flatline, theelectrodes 38, 39 are likely covered by a release liner; in this case,the microcontroller 61 determines that the electrodes 38, 39 are not incontact with the sternum 13. On the other hand, if processing of themeasured voltage detects at least that the electrodes 38, 39 have sensedat least a portion of a typical ECG waveform, such as the one shownbelow with reference to FIG. 12, the microcontroller 61 can determinethat the monitor 12 is adhered to the sternum 13. For instance, an Rwave is distinctly different from noise and can be easily detected by anR-wave detection algorithm that can be implemented by the microprocessor61; upon detecting that the electrodes 38, 39 sensed an R-wave based onthe measured voltage, the microcontroller 61 can determine that themonitor 12 is adhered to the patient 10, 11.

In a further embodiment, the contact with the sternum 13 can also bedetermined by the front end 63 or another circuit interfaced to themicrocontroller 61 by measuring the impedance of the electrodes 38, 39.Once the electrodes 38, 39 are adhered to the patient's 10, 11 skin andare measuring voltage of the body surface potentials, the impedance ofthe electrodes 38, 39 differs from the impedance when the electrodes 38,39 are not in contact with the skin, with the electrodes 38, 39 having ahigher impedance when not adhered to the patient's skin. By comparingthe predetermined impedance of the electrodes 38, 39 when the electrodes38, 39 are not in contact with the patient's skin to a measuredimpedance, the microcontroller 61 can detect that the contact betweenthe sternum 13 and the electrodes 38, 39 has been established. In afurther embodiment, the microcontroller 61 can determine that theelectrodes 38, 39 are connected to the sternum 13 when the measuredimpedance falls into a predetermined value range. Other ways todetermine the adherence are possible. Multiple sensors and input sourcescan be used by the microcontroller 61 to best determine if the monitor12 is in use and should start recording. For example, as furtherdescribed below, in one embodiment, the microcontroller 61 startschecking for the contact of the electrodes 38, 39 with the sternum 13only after receiving actigraphy data indicating that the monitor 12 isbeing worn by the patient 10, 11.

The circuitry 60 of the monitor recorder 14 also includes a flash memory62, which the microcontroller 61 uses for storing ECG monitoring dataand other physiology and information. The flash memory 62 also drawspower externally from the battery provided on the electrode patch 15 viaa pair of the electrical contacts 56. Data is stored in a serial flashmemory circuit, which supports read, erase and program operations over acommunications bus. The flash memory 62 enables the microcontroller 61to store digitized ECG data. The communications bus further enables theflash memory 62 to be directly accessed externally over the externalconnector 65 when the monitor recorder 14 is interfaced to a downloadstation.

The circuitry 60 of the monitor recorder 14 further includes anactigraphy sensor 64 implemented as a 3-axis accelerometer. Theaccelerometer may be configured to generate interrupt signals to themicrocontroller 61 by independent initial wake up and free fall events,as well as by device position. In addition, the actigraphy provided bythe accelerometer can be used during post-monitoring analysis to correctthe orientation of the monitor recorder 14 if, for instance, the monitorrecorder 14 has been inadvertently installed upside down, that is, withthe monitor recorder 14 oriented on the electrode patch 15 towards thepatient's feet, as well as for other event occurrence analyses, such asdescribed in commonly-assigned U.S. Pat. No. 9,737,224, issued Aug. 22,2017, the disclosure of which is incorporated by reference.

In addition, the actigraphy sensor 64 can be used to determine whetherthe monitor 12 is attached to the patient 10, 11. The actigraphy datacollected by the actigraphy sensor 64 can be identified as indicative ofthe monitor 12 being worn by the patient based on the data satisfyingone or more of certain thresholds of acceleration and deceleration, thefrequency with which the actigraphy data is generated, and a duration oftime during which the data is generated. For example, walking can berecognized by a variance of over 0.02 g (g-force) in the verticalacceleration within a frequency range of 1-3 Hz. Actigraphy dataindicative of walking can be set as indicative of the monitor 12 beingworn by the patient 12. Other kinds of actigraphy data, based on otherthresholds, can also be set as the monitor being attached. Following thereceipt of such data from the actigraphy sensor 34, the microcontroller61 can begin to check whether the electrodes 38, 39 are connected to thepatient 10, 11. The circuitry 60 of the monitor recorder 14 includes awireless transceiver 69 that can provides wireless interfacingcapabilities. The wireless transceiver 69 also draws power externallyfrom the battery provided on the electrode patch 15 via a pair of theelectrical contacts 56. The wireless transceiver 69 can be implementedusing one or more forms of wireless communications, including the IEEE802.11 computer communications standard, that is Wi-Fi; the 4G mobilephone mobile standard; the Bluetooth® data exchange standard; or otherwireless communications or data exchange standards and protocols.

The wireless transceiver used 69 can minimize the drain on the batteryprovided on the electrode patch 15 or another source that is used topower the monitor 12 by being implemented using a low energycommunication standard. For example, one such standard is the Bluetooth®4.0 standard. While the Bluetooth® 4.0 standard does not have a similarcommunication range to previous versions of the standard, the Bluetooth®4.0 standard significantly reduces the power consumption during wirelesscommunication when compared to the other standards. Further, thestandard is optimized for sending small packets of data, which can beused to communicate collected ECG data in near-real time; in oneembodiment, the wireless transceiver can send data packets that includephysiological data once every four seconds, allowing for continuoustransfer of the collected electrocardiographic and other kinds of data.Thus, implementing the wireless transceiver 69 using the Bluetooth® 4.0standard to communicate with other devices compatible with the standard,such as the mobile device 132, minimizes the consumption of power suchcommunication requires, extending the time that the monitor 12 cancontinuously conduct physiological monitoring.

Further, while many communication standards require communicatingdevices to be within a short range of each other, the range within whichthe wireless transceiver 69 can communicate with devices can be extendedby implementing the transceiver 69 using standards that allow thetransceiver 69 to have cellular phone capabilities such as accessing atelecommunications network, such as the Internet or a cellular network.For example, the standards such as the Bluetooth® 4.2 and the Wi-Fi®standards allow the transceiver 69 to connect to the Internet, thoughother standards can also be used to establish the Internet connection.When implemented using the Bluetooth 4.2 or the Wi-Fi® standards, thewireless transceiver 69 can communicate with other phones as well asother kinds of devices, such as activity sensors 131, mobile devices132, the server 122, personal computer 129, or other computing deviceconnectable over the network 121, to download and offload data over agreat distance via the Internet. Similarly, the wireless transceiver 69can include a cellular chipset that uses a cellular protocol, such asHigh Speed Packet Access Protocol (HSPA), though other protocols can beused, to access a cellular network and interface with devices such asother phones via the cellular network. Other standards allowing thewireless transceiver 69 have cellular phone capabilities are possible.

In one embodiment, a part of the functions required by the Bluetooth 4.0or another wireless standard is carried out by the microcontroller 61interfaced to the wireless transceiver 69. In a further embodiment, aseparate chip carrying out these functions can be also interfaced to themicrocontroller 61.

The microcontroller 61 includes an expansion port that also utilizes thecommunications bus. External devices, separately drawing powerexternally from the battery provided on the electrode patch 15 or othersource, can interface to the microcontroller 61 over the expansion portin half duplex mode. For instance, an external physiology sensor can beprovided as part of the circuitry 60 of the monitor recorder 14, or canbe provided on the electrode patch 15 with communication with themicrocontroller 61 provided over one of the electrical contacts 56. Thephysiology sensor can include an SpO₂ sensor, blood pressure sensor,temperature sensor, respiratory rate sensor, glucose sensor, airflowsensor, volumetric pressure sensing, or other types of sensor ortelemetric input sources. For instance, the integration of an airflowsensor is described in commonly-assigned U.S. Pat. No. 9,364,155, issuedJun. 14, 2016, the disclosure which is incorporated by reference.

Finally, the circuitry 60 of the monitor recorder 14 includespatient-interfaceable components, including a tactile feedback button66, which a patient can press to mark events or to perform otherfunctions, and a buzzer 67, such as a speaker, magnetic resonator orpiezoelectric buzzer. The buzzer 67 can be used by the microcontroller61 to output feedback to a patient such as to confirm power up andinitiation of ECG monitoring. Still other components as part of thecircuitry 60 of the monitor recorder 14 are possible.

While the monitor recorder 14 operates under micro control, most of theelectrical components of the electrode patch 15 operate passively. FIG.10 is a functional block diagram showing the circuitry 70 of theextended wear electrode patch 15 of FIG. 4. The circuitry 70 of theelectrode patch 15 is electrically coupled with the circuitry 60 of themonitor recorder 14 through an external connector 74. The externalconnector 74 is terminated through the set of pads 34 provided on thebottom of the non-conductive receptacle 25, which electrically mate tocorresponding electrical contacts 56 protruding from the bottom surfaceof the sealed housing 50 to electrically interface the monitor recorder14 to the electrode patch 15.

The circuitry 70 of the electrode patch 15 performs three primaryfunctions. First, a battery 71 is provided in a battery compartmentformed on the bottom surface of the non-conductive receptacle 25. Thebattery 71 is electrically interfaced to the circuitry 60 of the monitorrecorder 14 as a source of external power. The unique provisioning ofthe battery 71 on the electrode patch 15 provides several advantages.First, the locating of the battery 71 physically on the electrode patch15 lowers the center of gravity of the overall wearable monitor 12 andthereby helps to minimize shear forces and the effects of movements ofthe patient and clothing. Moreover, the housing 50 of the monitorrecorder 14 is sealed against moisture and providing power externallyavoids having to either periodically open the housing 50 for the batteryreplacement, which also creates the potential for moisture intrusion andhuman error, or to recharge the battery, which can potentially take themonitor recorder 14 off line for hours at a time. In addition, theelectrode patch 15 is intended to be disposable, while the monitorrecorder 14 is a reusable component. Each time that the electrode patch15 is replaced, a fresh battery is provided for the use of the monitorrecorder 14, which enhances ECG monitoring performance quality andduration of use. Finally, the architecture of the monitor recorder 14 isopen, in that other physiology sensors or components can be added byvirtue of the expansion port of the microcontroller 61. Requiring thoseadditional sensors or components to draw power from a source external tothe monitor recorder 14 keeps power considerations independent of themonitor recorder 14. Thus, a battery of higher capacity could beintroduced when needed to support the additional sensors or componentswithout effecting the monitor recorders circuitry 60.

Second, the pair of ECG electrodes 38, 39 respectively provided on thedistal and proximal ends of the flexible circuit 32 are electricallycoupled to the set of pads 34 provided on the bottom of thenon-conductive receptacle 25 by way of their respective circuit traces33, 37. The signal ECG electrode 39 includes a protection circuit 72,which is an inline resistor that protects the patient from excessiveleakage current.

Last, in a further embodiment, the circuitry 70 of the electrode patch15 includes a cryptographic circuit 73 to authenticate an electrodepatch 15 for use with a monitor recorder 14. The cryptographic circuit73 includes a device capable of secure authentication and validation.The cryptographic device 73 ensures that only genuine, non-expired,safe, and authenticated electrode patches 15 are permitted to providemonitoring data to a monitor recorder 14, such as described incommonly-assigned U.S. Pat. No. 9,655,538, issued May 23, 2017, thedisclosure which is incorporated by reference.

The ECG front end circuit 63 measures raw cutaneous electrical signalsusing a driven reference that effectively reduces common mode noise,power supply noise and system noise, which is critical to preserving thecharacteristics of low amplitude cardiac action potentials, especiallythose signals from the atria. FIG. 15 is a schematic diagram 80 showingthe ECG front end circuit 63 of the circuitry 60 of the monitor recorder14 of FIG. 9 in accordance with one embodiment. The ECG front endcircuit 63 senses body surface potentials through a signal lead (“S1”)and reference lead (“REF”) that are respectively connected to the ECGelectrodes of the electrode patch 15. Power is provided to the ECG frontend circuit 63 through a pair of DC power leads (“VCC” and “GND”). Ananalog ECG signal (“ECG”) representative of the electrical activity ofthe patient's heart over time is output, which the micro controller 11converts to digital representation and filters, as further describedinfra.

The ECG front end circuit 63 is organized into five stages, a passiveinput filter stage 81, a unity gain voltage follower stage 82, a passivehigh pass filtering stage 83, a voltage amplification and activefiltering stage 84, and an anti-aliasing passive filter stage 85, plus areference generator. Each of these stages and the reference generatorwill now be described.

The passive input filter stage 81 includes the parasitic impedance ofthe ECG electrodes 38, 39 (shown in FIG. 8), the protection resistorthat is included as part of the protection circuit 72 of the ECGelectrode 39 (shown in FIG. 10), an AC coupling capacitor 87, atermination resistor 88, and filter capacitor 89. This stage passivelyshifts the frequency response poles downward there is a high electrodeimpedance from the patient on the signal lead S1 and reference lead REF,which reduces high frequency noise.

The unity gain voltage follower stage 82 provides a unity voltage gainthat allows current amplification by an Operational Amplifier (“Op Amp”)90. In this stage, the voltage stays the same as the input, but morecurrent is available to feed additional stages. This configurationallows a very high input impedance, so as not to disrupt the bodysurface potentials or the filtering effect of the previous stage.

The passive high pass filtering stage 83 is a high pass filter thatremoves baseline wander and any offset generated from the previousstage. Adding an AC coupling capacitor 91 after the Op Amp 90 allows theuse of lower cost components, while increasing signal fidelity.

The voltage amplification and active filtering stage 84 amplifies thevoltage of the input signal through Op Amp 91, while applying a low passfilter. The DC bias of the input signal is automatically centered in thehighest performance input region of the Op Amp 91 because of the ACcoupling capacitor 91.

The anti-aliasing passive filter stage 85 provides an anti-aliasing lowpass filter. When the microcontroller 61 acquires a sample of the analoginput signal, a disruption in the signal occurs as a sample and holdcapacitor that is internal to the microcontroller 61 is charged tosupply the signal for acquisition. The anti-alising low pass filterminimizes the disruption to the input signal.

The reference generator in subcircuit 86 drives a driven referencecontaining power supply noise and system noise to the reference leadREF. A coupling capacitor 87 is included on the signal lead S1 and apair of resistors 93 a, 93 b inject system noise into the reference leadREF. The reference generator is connected directly to the patient,thereby avoiding the thermal noise of the protection resistor that isincluded as part of the protection circuit 72.

In contrast, conventional ECG lead configurations try to balance signaland reference lead connections. The conventional approach suffers fromthe introduction of differential thermal noise, lower input common moderejection, increased power supply noise, increased system noise, anddifferential voltages between the patient reference and the referenceused on the device that can obscure, at times, extremely, low amplitudebody surface potentials.

Here, the parasitic impedance of the ECG electrodes 38, 39, theprotection resistor that is included as part of the protection circuit72 and the coupling capacitor 87 allow the reference lead REF to beconnected directly to the skin's surface without any further components.As a result, the differential thermal noise problem caused by pairingprotection resistors to signal and reference leads, as used inconventional approaches, is avoided.

In a further embodiment, the circuitry 70 of the electrode patch 15includes a wireless transceiver 75, in lieu the including of thewireless transceiver 69 in the circuitry 60 of the monitor recorder 14,which interfaces with the microcontroller 61 over the microcontroller'sexpansion port via the external connector 74. Similarly to the wirelesstransceiver 69, the wireless transceiver 75 can be implemented using astandard that allows to conserve battery power, such as the Bluetooth®4.0 standard, though other standards are possible. Further, similarly tothe wireless transceiver 69, the wireless transceiver 75 can beimplemented using a standard that allows the transceiver 75 to havecellular phone capabilities such as accessing a telecommunicationsnetwork such as the Internet or a cellular network using the standardsdescribed above with reference to the wireless transceiver 69, such asthe Bluetooth® 4.2 standard, a Wi-Fi standard, or a cellular standard.

The monitor recorder 14 continuously monitors the patient's heart rateand physiology. FIG. 11 is a flow diagram showing a monitorrecorder-implemented method 100 for monitoring ECG data for use in themonitor recorder 14 of FIG. 4. Initially, upon being connected to theset of pads 34 provided with the non-conductive receptacle 25 when themonitor recorder 14 is snapped into place, the microcontroller 61executes a power up sequence (step 101). During the power up sequence,the voltage of the battery 71 is checked, the state of the flash memory62 is confirmed, both in terms of operability check and availablecapacity, and microcontroller operation is diagnostically confirmed. Ina further embodiment, an authentication procedure between themicrocontroller 61 and the electrode patch 15 are also performed.

The microcontroller 61 further checks whether the electrodes 38, 39 arein contact with the patient's 10, 11 sternum 13—whether the monitor 12has been adhered to the patient 10, 11 (step 102). As mentioned above,microcontroller 61 can use the front end 63 to detect when theelectrodes 38, 39 are adhered the skin of the patient's sternum 13 basedon the ECG signals measured by the front end 63 through the electrodes38, 39. In one embodiment, following the power-up sequence, themicrocontroller 61 can continually check for the adherence such as byhaving the front end 63 measure voltage through the electrodes 38, 39and determining whether the measured voltage was due to cardiac actionpotentials, such as by detecting that an R-wave was sensed by theelectrodes 38, 39. Alternatively, or in addition to the detection basedon the sensed electrocardiographic signals, the contact can bedetermined by measuring impedance of the electrodes 38, 39. The contactdetermination can also be performed after an expiration of a certaintime intervals as determined by a timer. For example, themicrocontroller 61 can check the presence of the contact every severalminutes after the monitor 12 has been powered on. In one embodiment, thetimer can be a part of the firmware implemented by the microcontroller61. In a further embodiment, the timer can be a separate component ofthe circuitries 60 or 70. In a further embodiment, the microcontroller61 does not start checking for the contact change until receivingactigraphy data from the actigraphy sensor 64 that satisfies one or morepredetermined criteria and indicates that the monitor 12 has beenattached to a patient 10, 11. For example, actigraphy data whosefrequency and magnitude fits indicates the patient 10, 11 walking can beset as data indicative of the monitor 12 being attached to the patient.After receiving the data, the microcontroller 61 can check for thecontact through the front end 63 once or repetitively, upon expirationof successive time intervals as measured by the timer. Making sure thatthe monitor 12 is adhered to the patient 10, 11 before initiatingcollection of ECG data allows to conserve battery power and thus extendthe length of monitoring using a single power source. In one embodiment,electrocardiographic signals sensed during this step recorded, asfurther described below; in a further embodiment, the signals can bediscarded upon the determination by the microcontroller 61 that themonitor 12 is adhered to the patient 10, 11.

Upon detecting that the electrodes 38, 39 are adhered to the patient(step 102), the microcontroller 61 proceeds to continually execute amonitoring sequence defined by the firmware of the microcontroller 61,the sequence including the iterative processing loop (steps 103-112)executed by the microcontroller 61. During each iteration (step 103) ofthe processing loop, the ECG front end 63 (shown in FIGS. 9 and 15)continually senses the cutaneous ECG electrical signals (step 104) viathe ECG electrodes 38, 39 and is optimized to maintain the integrity ofthe P-wave. A sample of the ECG signal is read (step 105) by themicrocontroller 61 by sampling the analog ECG signal output front end63. FIG. 12 is a graph showing, by way of example, a typical ECGwaveform 190. The x-axis represents time in approximate units of tenthsof a second. The y-axis represents cutaneous electrical signal strengthin approximate units of millivolts. The P-wave 191 has a smooth,normally upward, that is, positive, waveform that indicates atrialdepolarization. The QRS complex usually begins with the downwarddeflection of a Q wave 192, followed by a larger upward deflection of anR-wave 193, and terminated with a downward waveform of the S wave 194,collectively representative of ventricular depolarization. The T wave195 is normally a modest upward waveform, representative of ventriculardepolarization, while the U wave 196, often not directly observable,indicates the recovery period of the Purkinje conduction fibers.

Sampling of the R-to-R interval enables heart rate informationderivation. For instance, the R-to-R interval represents the ventricularrate and rhythm, while the P-to-P interval represents the atrial rateand rhythm. Importantly, the PR interval is indicative ofatrioventricular (AV) conduction time and abnormalities in the PRinterval can reveal underlying heart disorders within the AV node or theHis-Purkinje fibers or even metabolic disorders, thus representinganother reason why the P-wave quality achievable by the extended wearambulatory electrocardiography and physiological sensor monitordescribed herein is medically unique and important. The long-termobservation of these ECG indicia, as provided through extended wear ofthe wearable monitor 12, provides valuable insights to the patient'scardiac function and overall well-being.

Returning to FIG. 11, in a further embodiment, optionally, the monitorrecorder 14 also continuously receives data from wearable physiologymonitors or activity sensors 131 and mobile devices 132 (shown in FIG.3). Optionally, If wireless data is available (step 106), a sample ofthe wireless is read (step 107) by the microcontroller 61. If wirelessdata is not available (step 106), the method 100 moves to step 108.

Each sampled ECG signal, in quantized and digitized form, is temporarilystaged in buffer (step 108), pending compression preparatory to storagein the flash memory 62 (step 109). If wireless data sample was read instep 106, the wireless data sample, in quantized and digitized form, istemporarily staged in the buffer (step 108), pending compressionpreparatory to storage in the flash memory 62 (step 109). Followingcompression, the compressed ECG digitized sample, and if present, thewireless data sample, is again buffered (step 110), then written to theflash memory 62 (step 111) using the communications bus. Processingcontinues (step 112), so long as the monitoring recorder 14 remainsconnected to the electrode patch 15 (and storage space remains availablein the flash memory 62), after which the processing loop is exited andexecution terminates. In a further embodiment, the microcontroller 61can periodically check, such as upon expiration of time intervalsmaintained by the timer, whether the monitor 61 remains attached to thepatient 10, 11 based on impedance of the electrodes 38, 39 andterminates the processing upon detecting that the monitor 12 has beendisconnected from the patient 10, 11. Still other operations and stepsare possible. In a further embodiment, the reading and storage of thewireless data takes place, in a conceptually-separate execution thread,such as described in commonly-assigned U.S. Pat. No. 10,165,946, issuedJan. 1, 2019, to Bardy et al., the disclosure of which is incorporatedby reference.

The monitor recorder 14 stores ECG data and other information in theflash memory 62 (shown in FIG. 9) using a proprietary format thatincludes data compression. As a result, data retrieved from a monitorrecorder 14 must first be converted into a format suitable for use bythird party post-monitoring analysis software. FIG. 13 is a flow diagramshowing a method 150 for offloading and converting ECG and otherphysiological data from a contact-activated extended wearelectrocardiography and physiological sensor monitor 12 in accordancewith one embodiment. The method 150 can be implemented in software andexecution of the software can be performed on a download station 125,which could be a programmer or other device, or a computer system,including a server 122 or personal computer 129, such as furtherdescribed supra with reference to FIG. 3, as a series of process ormethod modules or steps. For convenience, the method 150 will bedescribed in the context of being performed by a personal computer 136or other connectable computing device (shown in FIG. 3) as middlewarethat converts ECG data and other information into a format suitable foruse by a third-party post-monitoring analysis program. Execution of themethod 150 by a computer system would be analogous mutatis mutandis.

Initially, the download station 125 is connected to the monitor recorder14 (step 151), such as by physically interfacing to a set of terminals128 on a paired receptacle 127 or by wireless connection, if available.The data stored on the monitor recorder 14, including ECG andphysiological monitoring data, other recorded data, and otherinformation are retrieved (step 152) over a hard link 135 using acontrol program 137 (“Ctl”) or analogous application executing on apersonal computer 136 or other connectable computing device.

The data retrieved from the monitor recorder 14 is in a proprietarystorage format and each datum of recorded ECG monitoring data, as wellas any other physiological data or other information, must be converted,so that the data can be used by a third-party post-monitoring analysisprogram. Each datum of ECG monitoring data is converted by themiddleware (steps 153-159) in an iterative processing loop. During eachiteration (step 153), the ECG datum is read (step 154) and, ifnecessary, the gain of the ECG signal is adjusted (step 155) tocompensate, for instance, for relocation or replacement of the electrodepatch 15 during the monitoring period. Filtering described above withreference to FIG. 17 can also optionally take place during step 155.

In addition, depending upon the configuration of the wearable monitor12, other physiological data (or other information), including patientevents, such as a fall, peak activity level, sleep detection, detectionof patient activity levels and states, and so on, may be recorded alongwith the ECG monitoring data. For instance, actigraphy data may havebeen sampled by the actigraphy sensor 64 based on a sensed eventoccurrence, such as a sudden change in orientation due to the patienttaking a fall. In response, the monitor recorder 14 will embed theactigraphy data samples into the stream of data, including ECGmonitoring data, that is recorded to the flash memory 62 by themicrocontroller 61. Post-monitoring, the actigraphy data is temporallymatched to the ECG data to provide the proper physiological context tothe sensed event occurrence. As a result, the three-axis actigraphysignal is turned into an actionable event occurrence that is provided,through conversion by the middleware, to third party post-monitoringanalysis programs, along with the ECG recordings contemporaneous to theevent occurrence. Other types of processing of the other physiologicaldata (or other information) are possible.

Thus, during execution of the middleware, any other physiological data(or other information) that has been embedded into the recorded ECGmonitoring data is read (step 156) and time-correlated to the time frameof the ECG signals that occurred at the time that the otherphysiological data (or other information) was noted (step 157). Finally,the ECG datum, signal gain adjusted, if appropriate, and otherphysiological data, if applicable and as time-correlated, are stored ina format suitable to the backend software (step 158) used inpost-monitoring analysis.

In a further embodiment, the other physiological data, if apropos, isembedded within an unused ECG track. For example, the SCP-ENG standardallows multiple ECG channels to be recorded into a single ECG record.The monitor recorder 14, though, only senses one ECG channel. The otherphysiological data can be stored into an additional ECG channel, whichwould otherwise be zero-padded or altogether omitted. The backendsoftware would then be able to read the other physiological data incontext with the single channel of ECG monitoring data recorded by themonitor recorder 14, provided the backend software implemented changesnecessary to interpret the other physiological data. Still other formsof embedding of the other physiological data with formatted ECGmonitoring data, or of providing the other physiological data in aseparate manner, are possible.

Processing continues (step 159) for each remaining ECG datum, afterwhich the processing loop is exited and execution terminates. Stillother operations and steps are possible.

While the invention has been particularly shown and described asreferenced to the embodiments thereof, those skilled in the art willunderstand that the foregoing and other changes in form and detail maybe made therein without departing from the spirit and scope.

What is claimed is:
 1. A contact-activated extended wearelectrocardiography and physiological sensor monitor recorder,comprising: a sealed housing adapted to be removably secured into anon-conductive receptacle on a disposable extended wear electrode patch;and an electronic circuitry comprised within the sealed housing,comprising: an electrocardiographic front end circuit electricallyinterfaced to an externally-powered microcontroller and operable tosense voltage comprising electrocardiographic signals throughelectrocardiographic electrodes provided on the disposable extended wearelectrode patch once a removable release liner is removed from theelectrocardiographic electrodes, each of the electrocardiographicelectrodes adapted to be positioned axially along the midline of thesternum for capturing action potential propagation; an actigraphy sensorelectrically interfaced with the externally-powered microcontroller, theactitgraphy sensor operable to collect movement data when the sealedhousing is worn by the patient and to provide the movement datacollected when the sealed housing is worn by the patient to theexternally-powered micro-controller; a timer operable to measure one ormore time intervals following an execution of a power-up sequence by theexternally-powered microcontroller and a receipt of the movement datacollected when the sealed housing is worn by the patient by theexternally-powered microcontroller; the externally-poweredmicrocontroller electrically interfaced to the electrographic front endcircuit and operable to execute under micro programmable control throughfirmware that is stored in a program memory unit of the microcontroller,the microcontroller operable to execute the power-up sequence upon thesealed housing being secured into the non-conductive receptacle, toreceive the movement data collected when the sealed housing is worn bythe patient, to measure the voltage via the front end following anexpiration of each of the time intervals and to process the sensedvoltage following the measurement, determine the sensed voltage to berepresentative of one of the portion of the electrocardiographicwaveform and the release liner being attached to theelectrocardiographic electrodes during the processing, to detect anadherence of the electrodes to a patient upon determining the sensedvoltage to be representative of the at least the portion of theelectrocardiographic waveform and not the release liner being attachedto the electrocardiographic electrodes, and to start for a first timeduring a monitoring period an execution of a monitoring sequence storedas part of the firmware upon detecting the adherence, the monitoringsequence comprising sampling the electrocardiographic signals over themonitoring period and storing all of the sampled electrocardiographicsignals, wherein the timer initiates the measurement of another one ofthe time intervals upon the determination of the sensed voltage beingrepresentative of the release liner being attached to theelectrocardiographic electrodes; an externally-powered flash memoryelectrically interfaced with the microcontroller and operable to storethe samples of the electrocardiographic signals collected during theexecution of the monitoring sequence; and a wireless transceiverinterfaced with the externally-powered microcontroller and theexternally-powered flash memory, the wireless transceiver comprising acellular chipset operable to receive additional data associated with thepatient from one or more cellular phones over a cellular network and totransmit the stored samples of the electrocardiographic signals and theadditional data over the cellular network.
 2. A contact-activatedextended wear electrocardiography and physiological sensor monitorrecorder according to claim 1, wherein the wireless transceiver isfurther operable to wirelessly interface with one or more furtherexternal wireless-enabled devices.
 3. A contact-activated extended wearelectrocardiography and physiological sensor monitor recorder accordingto claim 2, wherein the wireless transceiver communicates to the one ormore further external wireless-enabled devices an alert generated basedon the samples.
 4. A contact-activated extended wear electrocardiographyand physiological sensor monitor recorder according to claim 1, whereinthe patient is referred for medical care based on the transmittedsamples.
 5. A contact-activated extended wear electrocardiography andphysiological sensor monitor recorder according to claim 1, thedisposable extended wear electrode patch further comprising: a flexiblebacking formed of an elongated strip of stretchable material with anarrow longitudinal midsection and, on each end, a contact surface atleast partially coated with an adhesive dressing provided as a crimprelief; the pair of the electrocardiographic electrodes conductivelyexposed on the contact surface of each end of the elongated strip; anon-conductive receptacle adhered to an outward-facing surface of theelongated strip and comprising electrical pads; and a flexible circuitaffixed on each end of the elongated strip as a strain relief andcomprising a pair of circuit traces electrically coupled to the pair ofelectrocardiographic electrodes and a pair of the electrical pads, atleast one of the circuit traces adapted to extend along the narrowlongitudinal midsection to serve as the strain relief.
 6. Acontact-activated extended wear electrocardiography and physiologicalsensor monitor recorder according to claim 1, wherein the timer is oneof interfaced to the externally-powered micro-controller or implementedby the externally-powered microcontroller.
 7. A contact-activatedambulatory electrocardiography monitor optimized for capturing lowamplitude cardiac action potential propagation, comprising: a disposableextended wear electrode patch comprising: a flexible backing comprisingstretchable material defined as an elongated strip with a narrowlongitudinal midsection, each end of the flexible backing comprising anadhesive contact surface adapted to serve as a crimp relief; a pair ofelectrocardiographic electrodes comprised on the contact surface of eachend of the flexible backing, each electrocardiographic electrodeconductively exposed for dermal adhesion and adapted to be positionedaxially along the midline of the sternum for capturing action potentialpropagation; a release liner removably attached to theelectrocardiographic electrodes; a non-conductive receptacle affixed toa non-contacting surface of the flexible backing and comprising anelectro mechanical docking interface; and a pair of flexible circuittraces affixed at each end of the flexible backing with each circuittrace connecting one of the electrocardiographic electrodes to thedocking interface, at least one of the circuit traces adapted to extendalong the narrow longitudinal midsection to serve as a strain relief;and an ambulatory electrocardiography monitor recorder comprising: awearable housing adapted to securely fit into the receptacle; andelectronic circuitry provided within the wearable housing and comprisingan external interface configured to be removably connected to theelectrocardiographic electrodes via the docking interface, furthercomprising: an electrocardiographic front end circuit adapted to sensevoltage comprising cardiac electrical potential differentials throughthe electrocardiographic electrodes when the release liner is removedfrom the electrocardiographic electrodes; an actigraphy sensorelectrically interfaced with a low-power microcontroller, theactitgraphy sensor operable to collect movement data when the sealedhousing is worn by the patient and to provide the movement datacollected when the sealed housing is worn by the patient to themicro-controller; a timer operable to measure one or more time intervalsfollowing an execution of a power-up sequence by the low-powermicrocontroller and a receipt of the movement data collected when thesealed housing is worn by the patient by the low-power microcontroller;the low power microcontroller in control of the electrographic front endcircuit and operable to execute over an extended monitoring period undermodular micro program control as specified in firmware, themicrocontroller further operable to execute the power-up sequence uponthe sealed housing being secured into the non-conductive receptacle, toreceive the movement data collected when the sealed housing is worn bythe patient, to measure the voltage via the electrocardiographic frontend following an expiration of each of the time intervals, to processthe sensed voltage, to determine the sensed voltage to be representativeof one of the portion of the electrocardiographic waveform and therelease liner being attached to the electrocardiographic electrodesduring the processing, to detect an adherence of the electrodes to apatient upon the determination that the sensed voltage represents the atleast the portion of the electrocardiographic waveform and not therelease liner being attached to the electrocardiographic electrodes, andto start for a first time during the extended monitoring period anexecution of a monitoring sequence stored as part of the firmware upondetecting the adherence, the monitoring sequence comprising sampling theelectrocardiographic signals over the extended monitoring period andstoring all of the sampled electrocardiographic signals, wherein thetimer initiates the measurement of another one of the time intervalsupon the determination of the sensed voltage being representative of therelease liner being attached to the electrocardiographic electrodes; anon-volatile memory electrically interfaced with the microcontroller andoperable to continuously store the samples of the electrocardiographicsignals collected during the execution of the monitoring sequencethroughout the extended monitoring period; and a wireless transceiverinterfaced with the low power microcontroller and the non-volatilememory, the wireless transceiver comprising a cellular chipsetconfigured to receive additional data associated with the patient fromone or more cellular phones over a cellular network and to transmit thestored samples of the electrocardiographic signals and the additionaldata over the cellular network.
 8. A contact-activated ambulatoryelectrocardiography monitoring patch optimized for capturing lowamplitude cardiac action potential propagation according to claim 7,wherein the electrocardiographic front end circuit is optimized to senseP-wave signals in the electrocardiographic signals.
 9. Acontact-activated ambulatory electrocardiography monitoring patchoptimized for capturing low amplitude cardiac action potentialpropagation according to claim 7, wherein the wireless transceiver isfurther operable to wirelessly interface with one or more furtherexternal wireless-enabled devices.
 10. A contact-activated ambulatoryelectrocardiography monitoring patch optimized for capturing lowamplitude cardiac action potential propagation according to claim 9,wherein the wireless transceiver communicates to the one or more furtherexternal wireless-enabled devices an alert generated based on thesamples.
 11. A contact-activated ambulatory electrocardiographymonitoring patch optimized for capturing low amplitude cardiac actionpotential propagation according to claim 7, wherein the patient isreferred for medical care based on the transmitted samples.
 12. Acontact-activated ambulatory electrocardiography monitoring patchoptimized for capturing low amplitude cardiac action potentialpropagation according to claim 7, wherein the timer is one of interfacedto the low-power microcontroller or implemented by the low-powermicrocontroller.